drm/i915: Move intel_crtc_scanline_offset()

I want to use intel_crtc_scanline_offset() in
intel_crtc_scanline_to_hw(). Relocate intel_crtc_scanline_offset()
a bit to avoid a forward declaration.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240528185647.7765-6-ville.syrjala@linux.intel.comReviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_vblank.c

@@ -188,6 +188,44 @@ static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc)
 	return scanline;
 }
 
+static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+
+	/*
+	 * The scanline counter increments at the leading edge of hsync.
+	 *
+	 * On most platforms it starts counting from vtotal-1 on the
+	 * first active line. That means the scanline counter value is
+	 * always one less than what we would expect. Ie. just after
+	 * start of vblank, which also occurs at start of hsync (on the
+	 * last active line), the scanline counter will read vblank_start-1.
+	 *
+	 * On gen2 the scanline counter starts counting from 1 instead
+	 * of vtotal-1, so we have to subtract one.
+	 *
+	 * On HSW+ the behaviour of the scanline counter depends on the output
+	 * type. For DP ports it behaves like most other platforms, but on HDMI
+	 * there's an extra 1 line difference. So we need to add two instead of
+	 * one to the value.
+	 *
+	 * On VLV/CHV DSI the scanline counter would appear to increment
+	 * approx. 1/3 of a scanline before start of vblank. Unfortunately
+	 * that means we can't tell whether we're in vblank or not while
+	 * we're on that particular line. We must still set scanline_offset
+	 * to 1 so that the vblank timestamps come out correct when we query
+	 * the scanline counter from within the vblank interrupt handler.
+	 * However if queried just before the start of vblank we'll get an
+	 * answer that's slightly in the future.
+	 */
+	if (DISPLAY_VER(i915) == 2)
+		return -1;
+	else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
+		return 2;
+	else
+		return 1;
+}
+
 /*
  * intel_de_read_fw(), only for fast reads of display block, no need for
  * forcewake etc.
@@ -467,44 +505,6 @@ void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc)
 	wait_for_pipe_scanline_moving(crtc, true);
 }
 
-static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
-{
-	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
-
-	/*
-	 * The scanline counter increments at the leading edge of hsync.
-	 *
-	 * On most platforms it starts counting from vtotal-1 on the
-	 * first active line. That means the scanline counter value is
-	 * always one less than what we would expect. Ie. just after
-	 * start of vblank, which also occurs at start of hsync (on the
-	 * last active line), the scanline counter will read vblank_start-1.
-	 *
-	 * On gen2 the scanline counter starts counting from 1 instead
-	 * of vtotal-1, so we have to subtract one.
-	 *
-	 * On HSW+ the behaviour of the scanline counter depends on the output
-	 * type. For DP ports it behaves like most other platforms, but on HDMI
-	 * there's an extra 1 line difference. So we need to add two instead of
-	 * one to the value.
-	 *
-	 * On VLV/CHV DSI the scanline counter would appear to increment
-	 * approx. 1/3 of a scanline before start of vblank. Unfortunately
-	 * that means we can't tell whether we're in vblank or not while
-	 * we're on that particular line. We must still set scanline_offset
-	 * to 1 so that the vblank timestamps come out correct when we query
-	 * the scanline counter from within the vblank interrupt handler.
-	 * However if queried just before the start of vblank we'll get an
-	 * answer that's slightly in the future.
-	 */
-	if (DISPLAY_VER(i915) == 2)
-		return -1;
-	else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI))
-		return 2;
-	else
-		return 1;
-}
-
 void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state,
 				      bool vrr_enable)
 {