platform/x86/amd/pmf: Add debugging message for missing policy data

If a machine advertises Smart PC support but is missing policy data
show a debugging message to help clarify why Smart PC wasn't enabled.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20240217014107.113749-2-mario.limonciello@amd.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/amd/pmf/tee-if.c

@@ -252,8 +252,10 @@ static int amd_pmf_start_policy_engine(struct amd_pmf_dev *dev)
 	cookie = readl(dev->policy_buf + POLICY_COOKIE_OFFSET);
 	length = readl(dev->policy_buf + POLICY_COOKIE_LEN);
 
-	if (cookie != POLICY_SIGN_COOKIE || !length)
+	if (cookie != POLICY_SIGN_COOKIE || !length) {
+		dev_dbg(dev->dev, "cookie doesn't match\n");
 		return -EINVAL;
+	}
 
 	/* Update the actual length */
 	dev->policy_sz = length + 512;