As of grub2 >= 2.02-95 calling grub2-install on an EFI partition will
fail with: "this utility cannot be used for EFI platforms because it
does not support UEFI Secure Boot." In the case of ironic deployments,
ironic-python-agent will call efibootmgr to set the local boot for
subsequent boots.
This change adds efibootmgr to the image as well so any other UEFI
menu changes can be made manually.
Change-Id: I765ded15da07d6227d1e337960e54ad0e0d6ca39