nilrt.inc: add efi to DISTRO_FEATURES and set EFI_PROVIDER
nilrt.inc: add efi to DISTRO_FEATURES and set EFI_PROVIDER

Required by oe-core which now supports multiple efi providers in a
more systematic manner (though support for systemd-boot or gumniboot
doesn't currently exist in our isoimage-isohybrid plugin to create
iso's with different efi bootloaders, it can be added though).

Signed-off-by: Ioan-Adrian Ratiu <7ec73abcfe099fc5574c01312b62768070c80980@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt