linux.core: Update Syscall analysis to use time#toNanos and event#getName

linux.core: Update Syscall analysis to use time#toNanos and event#getName

Using ITmfTimestamp#toNanos ensure that system calls will be in the same
units if mixed OS traces are used. Using event#getName is faster and simpler
to read than event#getType()#getName.

Change-Id: I70819a28dfdaa257fa6c484c5073f77610605427
Signed-off-by: Matthew Khouzam <matthew.khouzam@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/80967
Reviewed-by: Hudson CI
Reviewed-by: Jean-Christian Kouame <jean-christian.kouame@ericsson.com>
Tested-by: Jean-Christian Kouame <jean-christian.kouame@ericsson.com>