efi_loader: implement OpenProtocolInformation

efi_open_protocol_information provides the agent and controller
handles as well as the attributes and open count of an protocol
on a handle.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
[agraf: fix counting error]
Signed-off-by: Alexander Graf <agraf@suse.de>
1 file changed