target/s390x: Introduce constant when checking if PV header couldn't be decrypted

target/s390x: Introduce constant when checking if PV header couldn't be decrypted

Introduce a named constant when checking the Set Secure Configuration parameters
UV call return code for the case where no valid host key was found and therefore
the PV header couldn't be decrypted (0x108).

Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Gautam Gala <ggala@linux.ibm.com>
Message-ID: <20250423080915.1048123-2-ggala@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>