afs: Use cell for md5 inode numbers

afs: Use cell for md5 inode numbers

When calculating the inode number for a file with md5 inodes, include
the cell number in the calculation, in order to reduce collisions
between cells.

Reviewed-on: http://gerrit.openafs.org/4902
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 42943aead4db2bdf9b8ec01c3917eb1c9ac9eb76)

Change-Id: I5cf88ecd30a5813697dbf3b86964d53bb1f3915a
Reviewed-on: http://gerrit.openafs.org/7277
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>