This patch adds the necessary structures to use the watchdog
functionality of PRCMU.

The watchdog driver is named ux500_wdt.
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>