efi_loader: open_info in OpenProtocol

efi_open_protocol has to keep track of opened protocols.

OpenProtocol enters the agent and controller handle
information into this list.

A unit test is supplied with a subsequent patch.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>