drm/nv50/disp: min/max are reversed in nv50_crtc_gamma_set()

We should be taking the minimum here instead of the max.  It could lead
to a buffer overflow.

Fixes: 438d99e ('drm/nvd0/disp: initial crtc object implementation')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

a/drm/nv50_display.c b/drm/nv50_display.c
index f8e66c08b11a..4e384a2f99c3 100644

drivers/gpu/drm/nouveau/nv50_display.c

@@ -1265,7 +1265,7 @@ nv50_crtc_gamma_set(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
 		    uint32_t start, uint32_t size)
 {
 	struct nouveau_crtc *nv_crtc = nouveau_crtc(crtc);
-	u32 end = max(start + size, (u32)256);
+	u32 end = min_t(u32, start + size, 256);
 	u32 i;
 
 	for (i = start; i < end; i++) {