drm/i915/dp: remove static variable for aux last status

Add aux_busy_last_status to intel_dp. Don't bother with initializing to
all ones; the only difference is potentially missing logging for one
error case if the readout is all zeros.
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191002144138.7917-1-jani.nikula@intel.com

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

@@ -1185,6 +1185,7 @@ struct intel_dp {
 	/* sink or branch descriptor */
 	struct drm_dp_desc desc;
 	struct drm_dp_aux aux;
+	u32 aux_busy_last_status;
 	u8 train_set[4];
 	int panel_power_up_delay;
 	int panel_power_down_delay;

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

@@ -1347,13 +1347,12 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
 	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
 
 	if (try == 3) {
-		static u32 last_status = -1;
 		const u32 status = intel_uncore_read(uncore, ch_ctl);
 
-		if (status != last_status) {
+		if (status != intel_dp->aux_busy_last_status) {
 			WARN(1, "dp_aux_ch not started status 0x%08x\n",
 			     status);
-			last_status = status;
+			intel_dp->aux_busy_last_status = status;
 		}
 
 		ret = -EBUSY;