drm/radeon: fix ring commit padding

We don't need to pad anything if the number of dwords
written to the ring already matches the requirements.

Fixes some "writting more dword to ring than expected"
warnings.

Signed-off-by: Christian König <deathsimple@vodafone.de>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_ring.c

@@ -272,13 +272,8 @@ int radeon_ring_lock(struct radeon_device *rdev, struct radeon_ring *ring, unsig
 
 void radeon_ring_commit(struct radeon_device *rdev, struct radeon_ring *ring)
 {
-	unsigned count_dw_pad;
-	unsigned i;
-
 	/* We pad to match fetch size */
-	count_dw_pad = (ring->align_mask + 1) -
-		       (ring->wptr & ring->align_mask);
-	for (i = 0; i < count_dw_pad; i++) {
+	while (ring->wptr & ring->align_mask) {
 		radeon_ring_write(ring, ring->nop);
 	}
 	DRM_MEMORYBARRIER();