efi_loader: Change return type of efi_add_memory_map()

efi_loader: Change return type of efi_add_memory_map()

We currently have some inconsistent use of efi_add_memory_map()
throughout the code. In particular the return value of efi_add_memory_map()
is not interpreted the same way by various users in the codebase.

This patch does the following:

- Changes efi_add_memory_map() to return efi_status_t.
- Adds a method description to efi_add_memory_map().
- Changes efi_add_memory_map() to return EFI_SUCCESS
- Returns non-zero for error in efi_add_memory_map()
- Updates efi_allocate_pages() to new efi_add_memory_map()
- Updates efi_free_pages() to new efi_add_memory_map()
- Updates efi_carve_out_dt_rsv() to new efi_add_memory_map()
- Updates efi_add_runtime_mmio()  to new efi_add_memory_map()

Fixes: 5d00995c361c ("efi_loader: Implement memory allocation and map")
Fixes: 74c16acce30b ("efi_loader: Don't allocate from memory holes")
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Alexander Graf <agraf@csgraf.de>
Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>