usb: typec: tcpm: Error handling for tcpm_register_partner_altmodes

typec_partner_register_altmode returns ERR_PTR. Reset the pointer
altmode to NULL on failure.
Signed-off-by: Kyle Tso <kyletso@google.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200714033453.4044482-3-kyletso@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -1061,9 +1061,11 @@ static void tcpm_register_partner_altmodes(struct tcpm_port *port)
 	for (i = 0; i < modep->altmodes; i++) {
 		altmode = typec_partner_register_altmode(port->partner,
 						&modep->altmode_desc[i]);
-		if (!altmode)
+		if (IS_ERR(altmode)) {
 			tcpm_log(port, "Failed to register partner SVID 0x%04x",
 				 modep->altmode_desc[i].svid);
+			altmode = NULL;
+		}
 		port->partner_altmode[i] = altmode;
 	}
 }