s390/config: make the vector optimized crc function builtin

For all configs with CONFIG_BTRFS_FS = y we should also make the
optimized crc module builtin. Otherwise early mounts will fall
back to the software variant.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>