Windows: AFSWriteCommon collapse redundant condition

We never get non cached and yet paging IO.  Even if we did it would
be inappropriate to call CcCanIWrite.  Therefore, collapse two if
statements into one.

Change-Id: I95c9030836e4f7dc4f7867a8b8b09b97bf57b429
Reviewed-on: http://gerrit.openafs.org/9125
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Peter Scott <pscott@kerneldrivers.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Windows: Allow the Library to pend a write request

If the library pends a request pending memory becoming available
then the FS must ensure that the library stays loaded until the
IRP is completed.

Change-Id: Idbfdd84ecd364c99d3ad9cd8dd7e000f47be4b58
Reviewed-on: http://gerrit.openafs.org/9126
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>