analysis.lami: Add units to timestamp axis title

analysis.lami: Add units to timestamp axis title

Units are currently missing in the axis title when the axis is a
timestamp series. This patch adds units based on the axis timestamp
format pattern.

Bug: 493941

Change-Id: I6f03267c5a2704d4b729cc3d666dd30df533053d
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-on: https://git.eclipse.org/r/74093
Reviewed-by: Hudson CI
Reviewed-by: Patrick Tasse <patrick.tasse@gmail.com>
Tested-by: Patrick Tasse <patrick.tasse@gmail.com>
Reviewed-by: Alexandre Montplaisir <alexmonthy@efficios.com>