hw/sd/sdcard: Handle RPMB MAC field

hw/sd/sdcard: Handle RPMB MAC field

Implement correct setting of the MAC field when passing RPMB frames back
to the guest. Also check the MAC on authenticated write requests.

This depends on HMAC support for QCRYPTO_HASH_ALGO_SHA256 which is
always available via glib - assert this, just to be safe.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <b6f5698c0ca017871d54834f0c7bd4b4b6316bbd.1762261430.git.jan.kiszka@siemens.com>
Tested-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>