sh: Correct SUBARCH matching.

When configuring the kernel natively the uname matching is off,
so fix up the uname mangling to get the proper SUBARCH. Needs
an explicit range so that SH-5 doesn't break.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>