MAINTAINERS: hwmon/coretemp: Change maintainers

Huaxu and Rudolf want me to be the hwmon coretemp driver maintainer and
remove their names from the coretemp maintainer entry.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Rudolf Marek <r.marek@assembler.cz>
Acked-by: Huaxu Wan <huaxu.wan@intel.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>