efi_loader: provide efi_mem_desc version

Provide version of struct efi_mem_desc in efi_get_memory_map().

EFI_BOOT_SERVICES.GetMemoryMap() in UEFI specification v2.6 defines
memory descriptor version to 1. Linux kernel also expects descriptor
version to be 1 and prints following warning during boot if its not:

Unexpected EFI_MEMORY_DESCRIPTOR version 0

Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@gmail.com>