sh: Delete unnecessary mov in the interrupt exception entry point.

The INTEVT read at interrupt exception entry is uneccessary, as the read
is deferred until we are ready to enter do_IRQ(). The kgdb nmi path still
requires it, so move it there.

Signed-off-by: Aoi Shinkai <shinkoi2005@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>