sh: Move cpu/$CPU to arch/sh/cpu/$CPU

arch/sh/cpu/sh2/Makefile

arch/sh/cpu/sh2/cache.c

arch/sh/cpu/sh2/config.mk

arch/sh/cpu/sh2/cpu.c

arch/sh/cpu/sh2/interrupts.c

arch/sh/cpu/sh2/start.S

arch/sh/cpu/sh2/u-boot.lds

arch/sh/cpu/sh2/watchdog.c

arch/sh/cpu/sh3/Makefile

arch/sh/cpu/sh3/cache.c

arch/sh/cpu/sh3/config.mk

arch/sh/cpu/sh3/cpu.c

arch/sh/cpu/sh3/interrupts.c

arch/sh/cpu/sh3/start.S

arch/sh/cpu/sh3/u-boot.lds

arch/sh/cpu/sh3/watchdog.c

arch/sh/cpu/sh4/Makefile

arch/sh/cpu/sh4/cache.c

arch/sh/cpu/sh4/config.mk

arch/sh/cpu/sh4/cpu.c