ARM: k2g: Use board detection to wrap K2G GP specific calls

Certain peripherals used by K2G GP aren't used on K2G ICE evm. Or
configuration is slightly different. Therefore, use board detection to
deal with these variations.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>