Gallery2: fix display abnormal when reload photos.

tvEmptyAlbum is still shown because hideEmptyAlbumToast() not called
when mAlbumDataAdapter.size() != 0.

make sure don't create a new tvEmptyAlbum when showEmptyAlbumToast(),
and call hideEmptyAlbumToast() when mAlbumDataAdapter.size() != 0.

Change-Id: I494011e54b4e150801019a3e2f9b430fb9ed999a
CRs-Fixed: 955208