efi_loader: complete efi_pxe_mode struct definition

efi_loader: complete efi_pxe_mode struct definition

The efi_pxe_mode struct which represents the PXE_BASE_CODE_PROTOCOL
Replace the placeholder paddings in the efi_pxe_mode struct with the
actual fields as defined in UEFI's PXE Base Code Protocol.  Since
our efi_ip_address is a simple char array set a specific alignment
to the efi_ip_address fields, as expected by the UEFI spec.

Signed-off-by: Patrick Wildt <patrick@blueri.se>
[agraf: s/pxe_discovervalid/pxe_discover_valid]
Signed-off-by: Alexander Graf <agraf@suse.de>