mfd: lpc_ich: Do not touch SPI-NOR write protection bit on Apollo Lake

Just to be on the safe side, don't touch the bit. If write access to the
flash chip is needed, the BIOS needs to enable it explicitly.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>