vol: remove [UN]LOCKFILE data loss warnings on Windows

vol: remove [UN]LOCKFILE data loss warnings on Windows

Cast to DWORD since the results of the mask and shift
are guaranteed to be 32-bit.  This avoids sixteen warnings.

Reviewed-on: http://gerrit.openafs.org/3695
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit fe9285f77a680b6e6d0995166f3c384aac676a8c)

Change-Id: Ic9a17074ce76d1676bb7d83e2e17d7c50e1c45a0
Reviewed-on: http://gerrit.openafs.org/3840
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>