disp: msm: add null pointer sanity checks

Add missing null pointer checks for variables
before referencing them.

Change-Id: I5592ea136d2759e0a4adb288492c6ef00ae79c4d
Signed-off-by: Prashant Singh <prasin@codeaurora.org>

msm/msm_fb.c

@@ -395,7 +395,7 @@ struct drm_framebuffer *msm_framebuffer_init(struct drm_device *dev,
 				 + width * cpp
 				 + mode_cmd->offsets[i];
 
-			if (bos[i]->size < min_size) {
+			if (!bos[i] || bos[i]->size < min_size) {
 				ret = -EINVAL;
 				goto fail;
 			}