powerpc/configs: Re-enable POWER8 crc32c

The config option for the POWER8 crc32c recently changed from
CONFIG_CRYPT_CRC32C_VPMSUM to CONFIG_CRYPTO_CRC32C_VPMSUM. Update
the configs.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>