efi_loader: remove CONFIG_EFI_SETUP_EARLY

Since the commit a9bf024b ("efi_loader: disk: a helper function to
create efi_disk objects from udevice"), CONFIG_EFI_SETUP_EARLY option is
by default on and will never be turned off.

So just remove this option.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>