rx: New signature for rx event functions

rx: New signature for rx event functions

For a while now, we've had both new and old-style rx event callback
functions. Modify all of our event handlers, and the functions that
install them, to use only new style functions, and get rid of the
old-style function prototypes.

Change-Id: Ic7c568df9d191edb082fb41fb7705c54ca93cf48
Reviewed-on: http://gerrit.openafs.org/5839
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>