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.

Change-Id: I462903099426b4d2e940e749dd958e03a04f7eb1
Reviewed-on: http://gerrit.openafs.org/8149
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>