drm/amd: cleanup coding style a bit

Fix patch check warning:
WARNING: suspect code indent for conditional statements (8, 17)
+       if (obj && obj->use < 0) {
+                DRM_ERROR("RAS ERROR: Unbalance obj(%s) use\n", obj->head.name);

WARNING: braces {} are not necessary for single statement blocks
+       if (obj && obj->use < 0) {
+                DRM_ERROR("RAS ERROR: Unbalance obj(%s) use\n", obj->head.name);
+       }

Signed-off-by: Bernard Zhao <bernard@vivo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>