scripts: compliance: Add items to UNDEF_KCONFIG_ALLOWLIST

'MCUX_HW_CORE' and 'MCUX_HW_FPU_TYPE' are used in
modules/hal_nxp/device.cmake. It is a variable used
by MCUX SDK CMake.

Signed-off-by: Zhaoxiang Jin <Zhaoxiang.Jin_1@nxp.com>