Windows: AFSCommonWrite do not leak SectionObjectResource

If the write request is neither an extending write nor a non-cached
write and (liStartingByte.QuadPart + ulByteCount) >=
pFcb->Header.FileSize.QuadPart, then the SectionObjectResource pointer
will be leaked.  Instead release it before retrying.

Change-Id: Id1ea7a3829a6e2be19280f366e665a11e14fba62
Reviewed-on: http://gerrit.openafs.org/9888
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>