n1sdp_timer_sync: add module for timer synchronization

N1SDP implements timer synchronization module to synchronize timers
on master and slave chips in multichip environment.

This patch implements a driver to trigger the synchronization
mechanism between the chips.

Change-Id: I7a52916ab62a5eed82da9ebfb7a1d0fad1fbd621
Signed-off-by: Manoj Kumar <manoj.kumar3@arm.com>