usb: typec: tcpm: usb: typec: tcpm: Fix a signedness bug in tcpm_fw_get_caps()

The "port->typec_caps.data" and "port->typec_caps.type" variables are
enums and in this context GCC will treat them as an unsigned int so they
can never be less than zero.

Fixes: ae8a2ca8 ("usb: typec: Group all TCPCI/TCPM code together")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20191001120117.GA23528@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -4409,18 +4409,20 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
 	/* USB data support is optional */
 	ret = fwnode_property_read_string(fwnode, "data-role", &cap_str);
 	if (ret == 0) {
-		port->typec_caps.data = typec_find_port_data_role(cap_str);
-		if (port->typec_caps.data < 0)
-			return -EINVAL;
+		ret = typec_find_port_data_role(cap_str);
+		if (ret < 0)
+			return ret;
+		port->typec_caps.data = ret;
 	}
 
 	ret = fwnode_property_read_string(fwnode, "power-role", &cap_str);
 	if (ret < 0)
 		return ret;
 
-	port->typec_caps.type = typec_find_port_power_role(cap_str);
-	if (port->typec_caps.type < 0)
-		return -EINVAL;
+	ret = typec_find_port_power_role(cap_str);
+	if (ret < 0)
+		return ret;
+	port->typec_caps.type = ret;
 	port->port_type = port->typec_caps.type;
 
 	if (port->port_type == TYPEC_PORT_SNK)