wifi: cfg80211: Fix not unregister reg_pdev when load_builtin_regdb_keys() fails

In regulatory_init_db(), when it's going to return a error, reg_pdev
should be unregistered. When load_builtin_regdb_keys() fails it doesn't
do it and makes cfg80211 can't be reload with report:

sysfs: cannot create duplicate filename '/devices/platform/regulatory.0'
 ...
 <TASK>
 dump_stack_lvl+0x79/0x9b
 sysfs_warn_dup.cold+0x1c/0x29
 sysfs_create_dir_ns+0x22d/0x290
 kobject_add_internal+0x247/0x800
 kobject_add+0x135/0x1b0
 device_add+0x389/0x1be0
 platform_device_add+0x28f/0x790
 platform_device_register_full+0x376/0x4b0
 regulatory_init+0x9a/0x4b2 [cfg80211]
 cfg80211_init+0x84/0x113 [cfg80211]
 ...

Fixes: 90a53e44 ("cfg80211: implement regdb signature checking")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Link: https://lore.kernel.org/r/20221109090237.214127-1-chenzhongjin@huawei.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -4311,8 +4311,10 @@ static int __init regulatory_init_db(void)
 		return -EINVAL;
 
 	err = load_builtin_regdb_keys();
-	if (err)
+	if (err) {
+		platform_device_unregister(reg_pdev);
 		return err;
+	}
 
 	/* We always try to get an update for the static regdomain */
 	err = regulatory_hint_core(cfg80211_world_regdom->alpha2);