crypto: ccp - Fix sample application signature passing

When parameters are sent the PSP returns back it's own signature
for the application to verify the authenticity of the result.

Display this signature to the caller instead of the one the caller
sent.

Fixes: f40d42f ("crypto: ccp - Add a sample python script for Dynamic Boost Control")
Fixes: febe3ed ("crypto: ccp - Add a sample library for ioctl use")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

tools/crypto/ccp/dbc.c

@@ -68,5 +68,6 @@ int process_param(int fd, int msg_index, __u8 *signature, int *data)
 		return errno;
 
 	*data = tmp.param;
+	memcpy(signature, tmp.signature, sizeof(tmp.signature));
 	return 0;
 }

tools/crypto/ccp/dbc.py

@@ -57,7 +57,8 @@ def process_param(device, message, signature, data=None):
     if type(message) != tuple:
         raise ValueError("Expected message tuple")
     arg = ctypes.c_int(data if data else 0)
-    ret = lib.process_param(device.fileno(), message[0], signature, ctypes.pointer(arg))
+    sig = ctypes.create_string_buffer(signature, len(signature))
+    ret = lib.process_param(device.fileno(), message[0], ctypes.pointer(sig), ctypes.pointer(arg))
     if ret:
         handle_error(ret)
-    return arg, signature
+    return arg.value, sig.value