disp: msm: remove gem functions without callsites

Many upstream files and APIs have been removed in downstream
driver. Some function definintions are left dangling without
any caller. Remove the functions which are not used downstream.

Change-Id: I9f936e7cdac3be6f854b3c67725164fad785f0d4
Signed-off-by: Steve Cohen <quic_cohens@quicinc.com>

msm/msm_gem_prime.c

@@ -78,14 +78,6 @@ void msm_gem_prime_unpin(struct drm_gem_object *obj)
 		msm_gem_put_pages(obj);
 }
 
-struct dma_resv *msm_gem_prime_res_obj(struct drm_gem_object *obj)
-{
-	struct msm_gem_object *msm_obj = to_msm_bo(obj);
-
-	return msm_obj->resv;
-}
-
-
 struct drm_gem_object *msm_gem_prime_import(struct drm_device *dev,
 					    struct dma_buf *dma_buf)
 {