drm/xen-front: Drop pointless static qualifier in fb_destroy()

There is no need to have the 'struct drm_framebuffer *fb' variable
static since new value always be assigned before use it.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1548504338-114487-1-git-send-email-yuehaibing@huawei.com

drivers/gpu/drm/xen/xen_drm_front_kms.c

@@ -54,7 +54,7 @@ fb_create(struct drm_device *dev, struct drm_file *filp,
 	  const struct drm_mode_fb_cmd2 *mode_cmd)
 {
 	struct xen_drm_front_drm_info *drm_info = dev->dev_private;
-	static struct drm_framebuffer *fb;
+	struct drm_framebuffer *fb;
 	struct drm_gem_object *gem_obj;
 	int ret;