Comment 17 for bug 1785033

Test with Dell's machine on Xenial with the grub2 xenail-proposed, and update grub-efi-amd64
and grub-efi-amd64-signed packages
got the correct 64-bit efi linear frame buffer address

[ 0.923498] efifb: probing for efifb
[ 0.923506] efifb: framebuffer at 0x4000000000, using 8100k, total 8100k
[ 0.923507] efifb: mode is 1920x1080x32, linelength=7680, pages=1
[ 0.923507] efifb: scrolling: redraw
[ 0.923508] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0