hwmon: (jc42) Fix missing unlock on error in jc42_write()

Add the missing unlock before return from function jc42_write()
in the error handling case.

Fixes: 37dedaee8bc6 ("hwmon: (jc42) Convert register access and caching to regmap/regcache")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20221027062931.598247-1-yangyingliang@huawei.com
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>