This implements support for grub2 bootloader for uefi.
The elilo bootloader would be default bootloader. One
can configure to use grub2 by updating ironic.conf as:-
[pxe]
uefi_pxe_config_template=$pybasedir/drivers/modules/pxe_grub_config.template
uefi_pxe_bootfile_name=bootx64.efi
Implements: blueprint uefi-secure-boot-pxe-ilo
Depends-On: I5745fe5c30b0ba1eb67065218dec9c334884007a
Change-Id: Idf7b24cf2f14bef9bebb5efd49a30869c8661572
efa74c5fee