efi_loader: use efi_update_capsule_firmware() for capsule on disk

efi_loader: use efi_update_capsule_firmware() for capsule on disk

Since the efi_update_capsule() represents the UpdateCapsule() runtime
service, it has to handle the capsule flags and update ESRT. However
the capsule-on-disk doesn't need to care about such things.

Thus, the capsule-on-disk should use the efi_capsule_update_firmware()
directly instead of calling efi_update_capsule().

This means the roles of the efi_update_capsule() and capsule-on-disk
are different. We have to keep the efi_update_capsule() for providing
runtime service API at boot time.

Suggested-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>