drm: drm_rmdraw: Declare id and idx as signed so testing for < 0 works as intended.

Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/drm_drawable.c b/drivers/char/drm/drm_drawable.c
index ce7a027..de37d5f 100644
--- a/drivers/char/drm/drm_drawable.c
+++ b/drivers/char/drm/drm_drawable.c
@@ -132,7 +132,8 @@
 {
 	DRM_DEVICE;
 	drm_draw_t draw;
- 	unsigned int id, idx, shift;
+ 	int id, idx;
+ 	unsigned int shift;
 	unsigned long irqflags;
 	u32 *bitfield = dev->drw_bitfield;
 	unsigned int bitfield_length = dev->drw_bitfield_length;