compat_ioctl: fix block device compat ioctl regression

The conversion of handlers to compat_blkdev_ioctl accidentally
disabled handling of most ioctl numbers on block devices because
of a typo. Fix the one line to enable it all again.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>