There is no code for this config option and enabling it in defconfig
causes warnings from tools which are detecting unused and obsolete
kernel config flags since the flag will be completely missing from
effective build config after "make olddefconfig".
Fixes yocto kernel recipe build time warning:
WARNING: [kernel config]: This BSP contains fragments with warnings:
...
[INFO]: the following symbols were not found in the active
configuration:
- CONFIG_COMMON_CLK_NPCM8XX