drm/i915: Relocate intel_attached_dp()

We have uses for intel_attached_dp() outside of intel_dp.c. Move
it to a header.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191204180549.1267-7-ville.syrjala@linux.intel.comReviewed-by: Mika Kahola <mika.kahola@intel.com>

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1489,6 +1489,11 @@ static inline struct intel_dp *enc_to_intel_dp(struct intel_encoder *encoder)
 	return &enc_to_dig_port(encoder)->dp;
 }
 
+static inline struct intel_dp *intel_attached_dp(struct intel_connector *connector)
+{
+	return enc_to_intel_dp(intel_attached_encoder(connector));
+}
+
 static inline bool intel_encoder_is_dp(struct intel_encoder *encoder)
 {
 	switch (encoder->type) {

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

@@ -146,11 +146,6 @@ bool intel_dp_is_edp(struct intel_dp *intel_dp)
 	return intel_dig_port->base.type == INTEL_OUTPUT_EDP;
 }
 
-static struct intel_dp *intel_attached_dp(struct intel_connector *connector)
-{
-	return enc_to_intel_dp(intel_attached_encoder(connector));
-}
-
 static void intel_dp_link_down(struct intel_encoder *encoder,
 			       const struct intel_crtc_state *old_crtc_state);
 static bool edp_panel_vdd_on(struct intel_dp *intel_dp);