rsa: Do not allow 1024 RSA keys in FIPS mode

Previously, the condition was in generate_std, which is never called in
FIPS mode.

• cipher/rsa.c (generate_std): Remove dead code as FIPS is using 'generate_fips' (generate_fips): Do not allow 1024 bit key generation --

• Signed-off-by: Jakub Jelen <jjelen@redhat.com>