Xtensa port: Fixed Xtensa timer in case of tickles idle.

This driver was written for v1.5 before the introduction of the function
_sys_clock_final_tick_announce. At that time _sys_idle_elapsed_ticks was reset
to 0 automatically. Now that it is reset by the new function, the driver needed
to be fixed.

Change-Id: I039b4dbacb691aaf992b37e44404abd19a54a833
Signed-off-by: Mazen NEIFER <mazen@nestwave.com>
1 file changed