firmware: turris-mox-rwtm: fix reply status decoding function

The status decoding function mox_get_status() currently contains an
incorrect check: if the error status is not MBOX_STS_SUCCESS, it always
returns -EIO, so the comparison to MBOX_STS_FAIL is never executed and
we don't get the actual error code sent by the firmware.

Fix this.
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Fixes: 389711b3 ("firmware: Add Turris Mox rWTM firmware driver")
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

drivers/firmware/turris-mox-rwtm.c

@@ -147,11 +147,14 @@ MOX_ATTR_RO(pubkey, "%s\n", pubkey);
 
 static int mox_get_status(enum mbox_cmd cmd, u32 retval)
 {
-	if (MBOX_STS_CMD(retval) != cmd ||
-	    MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
+	if (MBOX_STS_CMD(retval) != cmd)
 		return -EIO;
 	else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
 		return -(int)MBOX_STS_VALUE(retval);
+	else if (MBOX_STS_ERROR(retval) == MBOX_STS_BADCMD)
+		return -ENOSYS;
+	else if (MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
+		return -EIO;
 	else
 		return MBOX_STS_VALUE(retval);
 }