gpgsm: Avoid double free when checking rsaPSS signatures.

* sm/certcheck.c (gpgsm_check_cms_signature): Do not free s_sig on
error. Its owned and freed by the caller.

This is part of
(cherry picked from commit dcb0b6fd4822107d68bcb046d4d0650d02c82522)

• GnuPG-bug-id: T7129
• Signed-off-by: Jakub Jelen <jjelen@redhat.com>
• Fixes-commit: 969abcf40cdfc65f3ee859c5e62889e1a8ccde91