sh: move CONFIG_{SH2, SH2A, SH3, SH4} to Kconfig

This commit moves CONFIG_SH2, CONFIG_SH2A, CONFIG_SH3, CONFIG_SH4
to Kconfig renaming into CONFIG_CPU_SH2, CONFIG_CPU_SH2A,
CONFIG_CPU_SH3, CONFIG_CPU_SH4, respectively because
arch/sh/Kconfig of Linux uses CONFIG_CPU_SH* convention.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>