In some circumstances, reset_timer_masked() was called be timer_init() in
order to perform architecture specific timer initialisation. In such
cases, the required code in reset_timer_masked() has been moved into
timer_init()
According to the PPC reference implementation the udelay() function is
responsible for resetting the watchdog timer as frequently as needed.
Most other architectures do not meet that requirement, so long-running
operations might result in a watchdog reset.
This patch adds a generic udelay() function which takes care of
resetting the watchdog before calling an architecture-specific
__udelay().
Signed-off-by: Ingo van Lil <inguin@gmx.de>