fix reiserfs_evict_inode end_writeback second call

reiserfs_evict_inode calls end_writeback two times hitting
kernel BUG at fs/inode.c:298 becase inode->i_state is I_CLEAR already.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>