BKL: Remove BKL from ext3 fill_super()

The BKL is protecting nothing than two memory allocations here.

Signed-off-by: Jan Blunck <jblunck@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>