drm/xen-front: fix pointer casts

Building for a 32-bit target results in warnings from casting
between a 32-bit pointer and a 64-bit integer. Fix the warnings
by casting those pointers to uintptr_t first.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180523113630.29811-1-andr2000@gmail.com

drivers/gpu/drm/xen/xen_drm_front.h

@@ -126,12 +126,12 @@ struct xen_drm_front_drm_info {
 
 static inline u64 xen_drm_front_fb_to_cookie(struct drm_framebuffer *fb)
 {
-	return (u64)fb;
+	return (uintptr_t)fb;
 }
 
 static inline u64 xen_drm_front_dbuf_to_cookie(struct drm_gem_object *gem_obj)
 {
-	return (u64)gem_obj;
+	return (uintptr_t)gem_obj;
 }
 
 int xen_drm_front_mode_set(struct xen_drm_front_drm_pipeline *pipeline,

drivers/gpu/drm/xen/xen_drm_front_shbuf.c

@@ -122,7 +122,7 @@ static void guest_calc_num_grefs(struct xen_drm_front_shbuf *buf)
 }
 
 #define xen_page_to_vaddr(page) \
-		((phys_addr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
+		((uintptr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
 
 static int backend_unmap(struct xen_drm_front_shbuf *buf)
 {