fips: Only test check_binary_integrity when fips_mode is enabled.

* src/fips.c (_gcry_fips_run_selftests): Check the status of fips_mode
before calling check_binary_integrity.

• GnuPG-bug-id: T4274
• Reported-by: Pedro Monreal
• Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>