adm8211: fix error return code in adm8211_probe()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: cc0b88cf ("[PATCH] Add adm8211 802.11b wireless driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1607071638-33619-1-git-send-email-zhangchangzhong@huawei.com