watchdog: ks8695_wdt: include mach/hardware.h instead of mach/timex.h.

ks8695_wdt needs KS8695_CLOCK_RATE, which is defined in
mach/hardware.h, which is pulled in by the include of mach/timex.h,
but the latter is going away, so just include mach/hardware.h
directly.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Lennert Buytenhek <buytenh@secretlab.ca>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>