drm/radeon/kms: use udelay for short delays

For usec delays use udelay instead of scheduling, this should
allow reclocking to happen faster.
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/atom.c

@@ -640,7 +640,8 @@ static void atom_op_delay(atom_exec_context *ctx, int *ptr, int arg)
 	uint8_t count = U8((*ptr)++);
 	SDEBUG("   count: %d\n", count);
 	if (arg == ATOM_UNIT_MICROSEC)
-		schedule_timeout_uninterruptible(usecs_to_jiffies(count));
+		udelay(count);
+	//	schedule_timeout_uninterruptible(usecs_to_jiffies(count));
 	else
 		schedule_timeout_uninterruptible(msecs_to_jiffies(count));
 }