clocksource: ti-dmtimer: avoid using mach/hardware.h

As a preparation for future omap1 multiplatform support, stop
using mach/hardware.h and instead include the omap1-io.h
for low-level register access to MOD_CONF_CTRL_1.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>