i2c: npcm7xx: Fix error handling in npcm_i2c_init()

A problem about i2c-npcm7xx create debugfs failed is triggered with the
following log given:

 [  173.827310] debugfs: Directory 'npcm_i2c' with parent '/' already present!

The reason is that npcm_i2c_init() returns platform_driver_register()
directly without checking its return value, if platform_driver_register()
failed, it returns without destroy the newly created debugfs, resulting
the debugfs of npcm_i2c can never be created later.

 npcm_i2c_init()
   debugfs_create_dir() # create debugfs directory
   platform_driver_register()
     driver_register()
       bus_add_driver()
         priv = kzalloc(...) # OOM happened
   # return without destroy debugfs directory

Fix by removing debugfs when platform_driver_register() returns error.

Fixes: 56a1485b ("i2c: npcm7xx: Add Nuvoton NPCM I2C controller driver")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Tali Perry <tali.perry@nuvoton.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-npcm7xx.c

@@ -2393,8 +2393,17 @@ static struct platform_driver npcm_i2c_bus_driver = {
 
 static int __init npcm_i2c_init(void)
 {
+	int ret;
+
 	npcm_i2c_debugfs_dir = debugfs_create_dir("npcm_i2c", NULL);
-	return platform_driver_register(&npcm_i2c_bus_driver);
+
+	ret = platform_driver_register(&npcm_i2c_bus_driver);
+	if (ret) {
+		debugfs_remove_recursive(npcm_i2c_debugfs_dir);
+		return ret;
+	}
+
+	return 0;
 }
 module_init(npcm_i2c_init);