Misc changes for clean compilation of freedom-kl25z config

arch/arm/Kconfig

arch/arm/src/kl/Kconfig

arch/arm/src/kl/kl_clockconfig.c

arch/arm/src/kl/kl_clockconfig.c_orig

arch/arm/src/kl/kl_internal.h

arch/arm/src/kl/kl_lowputc.c

arch/arm/src/kl/kl_serial.c

arch/arm/src/kl/kl_start.c

configs/Kconfig

configs/freedom-kl25z/README.txt

configs/freedom-kl25z/include/board.h

configs/freedom-kl25z/nsh/defconfig

configs/freedom-kl25z/ostest/defconfig

configs/freedom-kl25z/scripts/ld.script_old