ipmi: kcs_bmc: Fix a memory leak in the error handling path of 'kcs_bmc_serio_add_device()'

In the unlikely event where 'devm_kzalloc()' fails and 'kzalloc()'
succeeds, 'port' would be leaking.

Test each allocation separately to avoid the leak.

Fixes: 3a3d2f6a4c64 ("ipmi: kcs_bmc: Add serio adaptor")
Signed-off-by: Christophe JAILLET <[e-mail]>
Message-Id: <ecbfa15e94[e-mail]>
Reviewed-by: Andrew Jeffery <[e-mail]>
Signed-off-by: Corey Minyard <[e-mail]>

drivers/char/ipmi/kcs_bmc_serio.c

···
 	struct serio *port;
 
 	priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
 
 	/* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
-	if (!(priv && port))
+	if (!port)
 		return -ENOMEM;
 
 	port->id.type = SERIO_8042;