LINUX: Avoid 'wakeup' define

LINUX: Avoid 'wakeup' define

Make 'wakeup' a static inline function instead of redefining 'wakeup',
so we can use the keyword 'wakeup' elsewhere.

Specifically, 'wakeup' is used in some Linux kernel structures, so
redefining it can confuse some things.

Reviewed-on: http://gerrit.openafs.org/8149
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 94115df4352b872ae096977d9a77fad935864688)

Change-Id: I6dadad579bf62677c76fd72be6a4ebe7e66a5c60
Reviewed-on: https://gerrit.openafs.org/12366
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>