drm/scdc-helper: Use consistent error reporting

The error messages generated by the SCDC helpers are somewhat
inconsistent with other DRM errors and even with other errors in the
same file. Fix them all up to use a common format.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170901144430.19164-2-thierry.reding@gmail.com

drivers/gpu/drm/drm_scdc_helper.c

@@ -141,7 +141,7 @@ bool drm_scdc_get_scrambling_status(struct i2c_adapter *adapter)
 
 	ret = drm_scdc_readb(adapter, SCDC_SCRAMBLER_STATUS, &status);
 	if (ret < 0) {
-		DRM_ERROR("Failed to read scrambling status, error %d\n", ret);
+		DRM_ERROR("Failed to read scrambling status: %d\n", ret);
 		return false;
 	}
 
@@ -168,7 +168,7 @@ bool drm_scdc_set_scrambling(struct i2c_adapter *adapter, bool enable)
 
 	ret = drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config);
 	if (ret < 0) {
-		DRM_ERROR("Failed to read tmds config, err=%d\n", ret);
+		DRM_ERROR("Failed to read tmds config: %d\n", ret);
 		return false;
 	}
 
@@ -179,7 +179,7 @@ bool drm_scdc_set_scrambling(struct i2c_adapter *adapter, bool enable)
 
 	ret = drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config);
 	if (ret < 0) {
-		DRM_ERROR("Failed to enable scrambling, error %d\n", ret);
+		DRM_ERROR("Failed to enable scrambling: %d\n", ret);
 		return false;
 	}
 
@@ -223,7 +223,7 @@ bool drm_scdc_set_high_tmds_clock_ratio(struct i2c_adapter *adapter, bool set)
 
 	ret = drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config);
 	if (ret < 0) {
-		DRM_ERROR("Failed to read tmds config, err=%d\n", ret);
+		DRM_ERROR("Failed to read tmds config: %d\n", ret);
 		return false;
 	}
 
@@ -234,7 +234,7 @@ bool drm_scdc_set_high_tmds_clock_ratio(struct i2c_adapter *adapter, bool set)
 
 	ret = drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config);
 	if (ret < 0) {
-		DRM_ERROR("Failed to set TMDS clock ratio, error %d\n", ret);
+		DRM_ERROR("Failed to set TMDS clock ratio: %d\n", ret);
 		return false;
 	}