drm/msm: remove unused variable

After the drm_device_is_unplugged() was removed, the 'dev' variable is now
unused, and we get a warning for that:

drivers/gpu/drm/msm/msm_fbdev.c: In function 'msm_fbdev_mmap':
drivers/gpu/drm/msm/msm_fbdev.c:65:21: error: unused variable 'dev' [-Werror=unused-variable]

This removes the variable as well.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: e9f8250f ("drm/msm: remove the drm_device_is_unplugged check")
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1455181810-3910161-1-git-send-email-arnd@arndb.de

drivers/gpu/drm/msm/msm_fbdev.c

@@ -62,7 +62,6 @@ static int msm_fbdev_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	struct drm_fb_helper *helper = (struct drm_fb_helper *)info->par;
 	struct msm_fbdev *fbdev = to_msm_fbdev(helper);
 	struct drm_gem_object *drm_obj = fbdev->bo;
-	struct drm_device *dev = helper->dev;
 	int ret = 0;
 
 	ret = drm_gem_mmap_obj(drm_obj, drm_obj->size, vma);