Remove unused -k argument to fileserver

It has been unused since the LWP fileserver was removed.
It was used to set the LWP stack size.

Change-Id: I2ffd3a2f02049a307b668a46b62b31dc9bc128a8
Reviewed-on: http://gerrit.openafs.org/11527
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: D Brashear <shadow@your-file-system.com>