ARM: OMAP2+: PM debug: fix the use of debugfs_create_* API

Check the return code pointer value from debugfs_create_dir for error
or NULL.
Also added an additional check to prevent the creation of a 'suspend'
entry at the debugfs root in case a power domain directory cannot be
created.
Signed-off-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NKevin Hilman <khilman@ti.com>

arch/arm/mach-omap2/pm-debug.c

@@ -220,8 +220,8 @@ static int __init pwrdms_setup(struct powerdomain *pwrdm, void *dir)
 		return 0;
 
 	d = debugfs_create_dir(pwrdm->name, (struct dentry *)dir);
-
-	(void) debugfs_create_file("suspend", S_IRUGO|S_IWUSR, d,
+	if (!(IS_ERR_OR_NULL(d)))
+		(void) debugfs_create_file("suspend", S_IRUGO|S_IWUSR, d,
 			(void *)pwrdm, &pwrdm_suspend_fops);
 
 	return 0;
@@ -264,7 +264,7 @@ static int __init pm_dbg_init(void)
 		return 0;
 
 	d = debugfs_create_dir("pm_debug", NULL);
-	if (IS_ERR(d))
+	if (IS_ERR_OR_NULL(d))
 		return PTR_ERR(d);
 
 	(void) debugfs_create_file("count", S_IRUGO,