crypto: aesni - remove unnecessary #define

The CPP identifier 'HAS_PCBC' is defined when the Kconfig
option CRYPTO_PCBC is set as 'y' or 'm', and is further
used in two ifdef blocks to conditionally compile source
code. This indirection hides the actual Kconfig dependency
and complicates readability. Moreover, it's inconsistent
with the rest of the ifdef blocks in the file, which
directly reference Kconfig options.

This patch removes 'HAS_PCBC' and replaces its occurrences
with the actual dependency on 'CRYPTO_PCBC' being set as
'y' or 'm'.

Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>