MAINTAINERS: Samsung: Update maintainer for PWM FAN and SAMSUNG THERMAL

Since I leave Samsung, I would like to step down from maintenance duties.
Bartek Zolnierkiewicz will replace.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>