libspdm: responder: Support PSK with ResponderContext

We currently advertise that we support

    Pre-Shared Key but does not provide ResponderContext for session key derivation.

Let's update this to instead advertise

    Pre-Shared Key and provides ResponderContext for session key derivation

The SPDM spec states that:

     the Responder is required to use ResponderContext if it can generate a nonce

which we can, so let's adertise ResponderContext.

This also allows the libspdm function libspdm_get_response_psk_finish() to
work correctly.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

src/libspdm/responder.rs

@@ -62,7 +62,7 @@ pub fn setup_capabilities(
         let mut data: u32 = SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_CERT_CAP
             | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_ENCRYPT_CAP
             | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_KEY_EX_CAP
-            | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_PSK_CAP_RESPONDER
+            | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_PSK_CAP_RESPONDER_WITH_CONTEXT
             | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_CHAL_CAP
             | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_MEAS_CAP_SIG
             | SPDM_GET_CAPABILITIES_RESPONSE_FLAGS_MAC_CAP