ecc: Do not allow skipping tests in FIPS Mode.

* cipher/ecc.c (ecc_generate): Do not allow skipping tests PCT tests
in FIPS mode.

The new FIPS specification requires to run the PCT without any
exceptions.

• GnuPG-bug-id: T6394
• Signed-off-by: Jakub Jelen <jjelen@redhat.com>