platform/x86: amd-pmc: Fix missing unlock on error in amd_pmc_send_cmd()

BugLink: https://bugs.launchpad.net/bugs/1934809

Add the missing unlock before return from function amd_pmc_send_cmd()
in the error handling case.

Fixes: 95e1b60 ("platform/x86: amd-pmc: Fix command completion code")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210715074327.1966083-1-yangyingliang@huawei.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
(cherry picked from commit 95edbbf linux-next)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>

drivers/platform/x86/amd-pmc.c

@@ -275,7 +275,7 @@ static int amd_pmc_send_cmd(struct amd_pmc_dev *dev, bool set, u32 *data, u8 msg
 				PMC_MSG_DELAY_MIN_US * RESPONSE_REGISTER_LOOP_MAX);
 	if (rc) {
 		dev_err(dev->dev, "failed to talk to SMU\n");
-		return rc;
+		goto out_unlock;
 	}
 
 	/* Write zero to response register */