KEYS: asymmetric: Add missing dependencies of FIPS_SIGNATURE_SELFTEST

KEYS: asymmetric: Add missing dependencies of FIPS_SIGNATURE_SELFTEST

Since the signature self-test uses RSA and SHA-256, it must only be
enabled when those algorithms are enabled.  Otherwise it fails and
panics the kernel on boot-up.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202404221528.51d75177-lkp@intel.com
Fixes: 3cde3174eb91 ("certs: Add FIPS selftests")
Cc: stable@vger.kernel.org
Cc: Simo Sorce <simo@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>