s390x: Fix HMAC to fail update or final call when already finalized

s390x: Fix HMAC to fail update or final call when already finalized

After commit a5d1eadde1d566b528cfe495953300cd9f9fe1e9 the test step
'test_hmac_final_update_fail' of 'test_hmac' fails.

Return an error when update or final is used after the context has
already been finalized. Flag 'iimp' (intermediate-input-message-part)
must be 1 to allow an update or final call. If iimp is 0, then the
context has already been finalized.

Signed-off-by: Ingo Franzki <ifranzki@linux.ibm.com>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27781)