More NVDIMM work.

More NVDIMM work.

With this, it works with efibootmgr:

[root@testbox pjones]# LD_LIBRARY_PATH=/root/pjones efibootmgr -b 000E -C -d /dev/pmem12.2 -L pjones-test -l /dax-screw-aeI12d -v
BootCurrent: 000D
Timeout: 1 seconds
BootOrder: 000D
Boot000D* Red Hat Enterprise Linux	HD(1,GPT,727bbaeb-9766-4e3b-b374-d3f2dc9a0ab5,0x800,0x64000)/File(\EFI\redhat\shimx64.efi)
Boot000E* pjones-test	NVDIMM(829c5205-89a5-4581-9819-df7d7754c622)/File(\dax-screw-aeI12d)

(obviously this won't actually boot because /mnt/test is not the ESP and
dax-screw-aeI12d is just some random file I found sitting around, but
the EFI boot variable appears to be correct.)

Signed-off-by: Peter Jones <pjones@redhat.com>