loader.efi: efifb_gop_get_edid() is broken
First of all, we need gop handle, not protocol to read out the EDID. Then, to simplify our life, use EFI_OPEN_PROTOCOL_GET_PROTOCOL. This allows us to save from cleanup.
Also add back fallback to EFI_EDID_DISCOVERED_PROTOCOL_GUID, even as EFI_EDID_ACTIVE_PROTOCOL_GUID should do, we never know.
Testing done: confirm with framebuffer get, we do have EDID.