staging: imx-drm: Replace DRM_LOG_KMS() by DRM_DEBUG_KMS()

There are only a few users of the DRM_LOG_KMS() macro. We can simplify
the DRM code a bit by replacing them by DRM_DEBUG_KMS().

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/staging/imx-drm/ipuv3-plane.c b/drivers/staging/imx-drm/ipuv3-plane.c
index 34b642a..5128dc3 100644
--- a/drivers/staging/imx-drm/ipuv3-plane.c
+++ b/drivers/staging/imx-drm/ipuv3-plane.c
@@ -68,7 +68,7 @@
 
 	cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
 	if (!cma_obj) {
-		DRM_LOG_KMS("entry is null.\n");
+		DRM_DEBUG_KMS("entry is null.\n");
 		return -EFAULT;
 	}