Adds support for the EFI partition to be appended to fstab so the
filesystem can be automounted and EFI loader updated should the
deployed operating system need to do so.
This should enable bootloaders to be upgraded by linux based
operating systems after the instance has been deployed when
a partition image was utilized for the initial deployment.
Change-Id: Iec28a8841cc01ec8b01a3f5cca070c934c7a2531
Story: 2008070
Task: 40754