cpu: adapt to COREIF_NG removal

cpu/atmega1281/Makefile.include

cpu/atmega2560/Makefile.include

cpu/atmega328p/Makefile.include

cpu/atmega_common/irq_arch.c

cpu/atmega_common/thread_arch.c

cpu/cortexm_common/irq_arch.c

cpu/cortexm_common/thread_arch.c

cpu/lm4f120/cpu.c

cpu/mips32r2_common/cpu.c

cpu/mips32r2_common/irq_arch.c

cpu/mips32r2_common/periph/timer.c

cpu/mips32r2_common/thread_arch.c

cpu/msp430_common/cpu.c

cpu/native/irq_cpu.c

cpu/native/native_cpu.c

cpu/nrf52/vectors.c

makefiles/arch/cortexm.inc.mk

makefiles/arch/mips.inc.mk