drm/exynos: 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: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
index e0db2b3..8371cbd 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
@@ -87,7 +87,7 @@
 		struct exynos_drm_gem_buf *buffer = exynos_drm_fb_buffer(fb, i);
 
 		if (!buffer) {
-			DRM_LOG_KMS("buffer is null\n");
+			DRM_DEBUG_KMS("buffer is null\n");
 			return -EFAULT;
 		}