efi_loader: Depend on BLK

efi_loader: Depend on BLK

In reworking the BLK usage in Kconfig, I found there's a few issues with
EFI_LOADER=y and BLK=n. In general, we can easily say that
lib/efi_loader/efi_file.c also should only be built with CONFIG_BLK.
That however leaves the bootmgr code, eficonfig code and then parts of
efi_device_path.c, efi_boottime.c and efi_setup.c which functionally
depend on BLK. While these calls can be if'd out, I'm unsure if the
result is usable. So rather than leave that buildable and imply that it
is, I'm leaving that combination non-buildable and commenting that
EFI_LOADER depends on BLK in the Kconfig currently.

Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>