Set kernel event logger timestamps to HW cycles

OS tick period (usually 10 ms) is not sufficiently precise for task
execution analysis (like processing CPU load per context)

With that modification, the timestamp used by the kernel event logger
is 32-bit LSB of platform HW timer (for example Lakemont APIC timer
for Quark SE).
This timer period is very small and leads to timestamp wraparound
happening quite often (e.g. every 134s for Quark SE).

This wraparound must be considered when analyzing kernel event logger
data and care must be taken when tickless idle is enabled and sleep
duration can exceed maximum HW timer value.

Change-Id: Idc545da8f828a7357a69d83ff25c9afd09dab3c4
Signed-off-by: Fabrice Olivero <fabrice.olivero@intel.com>