drm/i915/dsi: Replace MIPI command error message with debug message

Error message indicating that the same MIPI command is sent
consecutively is perhaps too strongly said. Let's replace that as a
debug message instead.
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1504252261-28964-3-git-send-email-mika.kahola@intel.com

drivers/gpu/drm/i915/intel_dsi.c

@@ -263,7 +263,7 @@ static int dpi_send_cmd(struct intel_dsi *intel_dsi, u32 cmd, bool hs,
 
 	/* XXX: old code skips write if control unchanged */
 	if (cmd == I915_READ(MIPI_DPI_CONTROL(port)))
-		DRM_ERROR("Same special packet %02x twice in a row.\n", cmd);
+		DRM_DEBUG_KMS("Same special packet %02x twice in a row.\n", cmd);
 
 	I915_WRITE(MIPI_DPI_CONTROL(port), cmd);