powerpc/8xx: Fix possible device node reference leak

The call to of_find_compatible_node() returns a node pointer with
refcount incremented thus it must be explicitly decremented after the
last usage.

irq_domain_add_linear() also calls of_node_get() to increase refcount,
so irq_domain() will not be affected when it is released.

Detected by coccinelle.

Fixes: a8db8cf0d8 ("irq_domain: Replace irq_alloc_host() with revmap-specific initializers")
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Peng Hao <peng.hao2@zte.com.cn>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/8xx/pic.c

@@ -153,10 +153,9 @@ int mpc8xx_pic_init(void)
 	if (mpc8xx_pic_host == NULL) {
 		printk(KERN_ERR "MPC8xx PIC: failed to allocate irq host!\n");
 		ret = -ENOMEM;
-		goto out;
 	}
-	return 0;
 
+	ret = 0;
 out:
 	of_node_put(np);
 	return ret;