drm/etnaviv: rename etnaviv_gem_vaddr to etnaviv_gem_vmap

This function follows the semantics of vmap() by returning
NULL in case of an error. To make things less confusing
rename it to make make both functions more closely related.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index b22712f..1da3d48 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -353,7 +353,7 @@
 	drm_gem_object_unreference_unlocked(obj);
 }
 
-void *etnaviv_gem_vaddr(struct drm_gem_object *obj)
+void *etnaviv_gem_vmap(struct drm_gem_object *obj)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);