drm/i915/dp: Convert link training error to debug message on disconnected sink

If a sink is disconnected it's expected that link training actions will
fail on it, so downgrade the error messages about such actions to be a
debug message. Such - expected - link training failures are more
frequent after a follow up patch, after which an active TypeC link is
reset after the sink is disconnected which also involves a link
training.

v2:
- Check the actual HPD state to handle the forced connector state case.
  (Vinod)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v1)
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230510103131.1618266-10-imre.deak@intel.com

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

@@ -38,10 +38,14 @@
 		    LT_MSG_PREFIX _format, \
 		    LT_MSG_ARGS(_intel_dp, _dp_phy), ## __VA_ARGS__)
 
-#define lt_err(_intel_dp, _dp_phy, _format, ...) \
-	drm_err(&dp_to_i915(_intel_dp)->drm, \
-		LT_MSG_PREFIX _format, \
-		LT_MSG_ARGS(_intel_dp, _dp_phy), ## __VA_ARGS__)
+#define lt_err(_intel_dp, _dp_phy, _format, ...) do { \
+	if (intel_digital_port_connected(&dp_to_dig_port(_intel_dp)->base)) \
+		drm_err(&dp_to_i915(_intel_dp)->drm, \
+			LT_MSG_PREFIX _format, \
+			LT_MSG_ARGS(_intel_dp, _dp_phy), ## __VA_ARGS__); \
+	else \
+		lt_dbg(_intel_dp, _dp_phy, "Sink disconnected: " _format, ## __VA_ARGS__); \
+} while (0)
 
 static void intel_dp_reset_lttpr_common_caps(struct intel_dp *intel_dp)
 {