This commit adds osal_get_monotonic_time() and
osal_monotonic_sleep(). These functions are designed to facilitate
synchronization with DC time, which can achieve nanosecond precision.
To support this functionality, the ec_timet structure has been
refactored to hold time values in nanoseconds, eliminating the need to
maintain separate time representations.
Change-Id: I039a006ccdb21ba35c437ab76e44e5153c711998
