config: Move AFS_LRALLOCSIZ to afs_args.h

AFS_LRALLOCSIZ is currently defined in afs/afs.h.  Other memory
related definitions such as AFS_SMALLOCSIZ and AFS_MDALLOCSIZ
are defined in config/afs_args.h.  Move AFS_LRALLOCSIZ to
config/afs_args.h for consistency.

Change-Id: Ie1e286c24be6a2def404a54355a2fa4b2c42330d
Reviewed-on: http://gerrit.openafs.org/11174
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>