greybus: protocol: send own protocol version while requesting it

The greybus specifications clearly say (for all protocols) that the
sender is responsible for sending the highest version of protocol it
supports, while it requests the same from the receiver.

But the greybus code never followed that.

Fix, this by always sending AP's version of the protocol, while
requesting the same from svc/module.

This also renames 'response' to 'version' in gb_protocol_get_version()
as it is used for both request/response.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>