sunxi: kconfig: Rename TARGET_SUN[45678]I to MACH_SUN[45678]I.

Now we have CONFIG_ARCH_SUNXI as the toplevel, CONFIG_MACH_SUN[45678]I as the
per-SoC option and leave CONFIG_TARGET_BLAH free for individual boards in the
future.

Done automatically with:
    sed -i -e 's/TARGET_\(SUN[45678]I\)/MACH_\1/g' $(git grep -l TARGET_SUN[45678]I)

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>