replace .wks with .wks.in and refer loader to EFI_PROVIDER
to enable different bootloader.
soft assign default EFI_PROVIDER "grub-efi" for genericx86.
(From meta-yocto rev: 11ecd2febed95e923c8cc68e2c438cd846a88d02)
Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>