Linux 4.4: key_payload has no member 'value'

Linux 4.4: key_payload has no member 'value'

In Linux 4.4 (146aa8b1453bd8f1ff2304ffb71b4ee0eb9acdcc) type-specific and
payload data have been merged. The payload is now accessed directly and has
no 'value' member anymore.

FIXES 132677

Reviewed-on: https://gerrit.openafs.org/12169
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 5067ee3ae11932a3f1c972c8f88b20afbd9e1d88)

Change-Id: I5a3e89b2676b463935e9a77042cbcd8ab812dc68
Reviewed-on: https://gerrit.openafs.org/12226
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>