drm/i915/tc: move legacy code out of the main _max_lane_count() func

This makes the code a bit more symmetric and readable, especially when
we start adding more display version-specific alternatives.
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230825081638.275795-4-luciano.coelho@intel.com

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

@@ -311,23 +311,12 @@ static int mtl_tc_port_get_max_lane_count(struct intel_digital_port *dig_port)
 	}
 }
 
-int intel_tc_port_fia_max_lane_count(struct intel_digital_port *dig_port)
+static int intel_tc_port_get_max_lane_count(struct intel_digital_port *dig_port)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
-	struct intel_tc_port *tc = to_tc_port(dig_port);
-	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
 	intel_wakeref_t wakeref;
-	u32 lane_mask;
-
-	if (!intel_phy_is_tc(i915, phy) || tc->mode != TC_PORT_DP_ALT)
-		return 4;
+	u32 lane_mask = 0;
 
-	assert_tc_cold_blocked(tc);
-
-	if (DISPLAY_VER(i915) >= 14)
-		return mtl_tc_port_get_max_lane_count(dig_port);
-
-	lane_mask = 0;
 	with_intel_display_power(i915, POWER_DOMAIN_DISPLAY_CORE, wakeref)
 		lane_mask = intel_tc_port_get_lane_mask(dig_port);
 
@@ -348,6 +337,23 @@ int intel_tc_port_fia_max_lane_count(struct intel_digital_port *dig_port)
 	}
 }
 
+int intel_tc_port_fia_max_lane_count(struct intel_digital_port *dig_port)
+{
+	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
+	struct intel_tc_port *tc = to_tc_port(dig_port);
+	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
+
+	if (!intel_phy_is_tc(i915, phy) || tc->mode != TC_PORT_DP_ALT)
+		return 4;
+
+	assert_tc_cold_blocked(tc);
+
+	if (DISPLAY_VER(i915) >= 14)
+		return mtl_tc_port_get_max_lane_count(dig_port);
+
+	return intel_tc_port_get_max_lane_count(dig_port);
+}
+
 void intel_tc_port_set_fia_lane_count(struct intel_digital_port *dig_port,
 				      int required_lanes)
 {