shell: Remove unused pointer_end_grab

shell_grab_end already does that for us.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
diff --git a/src/shell.c b/src/shell.c
index 57e6ab9..a9e4d4f 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -810,7 +810,6 @@
 	if (pointer->button_count == 0 &&
 	    state == WL_POINTER_BUTTON_STATE_RELEASED) {
 		shell_grab_end(shell_grab);
-		wl_pointer_end_grab(pointer);
 		free(grab);
 	}
 }
@@ -826,11 +825,9 @@
 		       struct wl_surface *surface, int32_t x, int32_t y)
 {
 	struct shell_grab *grab = (struct shell_grab *) base;
-	struct wl_pointer *pointer = base->pointer;
 
 	if (grab->grab.focus != surface) {
 		shell_grab_end(grab);
-		wl_pointer_end_grab(pointer);
 		free(grab);
 	}
 }