meta-facebook: Add support for phosphor-gpio-monitor

Added phosphor-gpio-monitor support for facebook platforms
to enable hot plug/unplug of host feature.

TESTED : Verified hot plug/unplug of all hosts are enabled
and tested in Facebook YosemiteV2 platform.

Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
Change-Id: I7ff6647942cdc979c2a3dc6f4c85c1273785cf65