efi_loader: open protocol information

When a protocol is opened the open protocol information must be updated.
The key fields of the open protocol information records are ImageHandle,
ControllerHandle, and Attributes.

Consider the Attributes field when determining if an open protocol
information record has to be updated or a new one has to be created.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>