greybus: let operation layer examine incoming data

greybus: let operation layer examine incoming data

Give the operation layer a chance to examine incoming data so that
it can handle it appropriately.

Treat the data as an operation message header.  If it's a response,
look up the operation it's associated with.  If it's not, create a
new operation.  Copy the incoming data into the request or response
buffer.  The next patch adds a work queue to pick up handling
the request or response from there.

Get rid of gb_operation_submit().  Instead, we have two functions,
one for sending an operation's request message, the other for
sending an operation's response message.

Not fully functional yet, still just filling things in...

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>