The sleep for I/O completion during an NFSv4.1 pNFS layout recall used
the wrong event value and could result in the "[nfscl]" thread hung
for the mount.
This patch fixes the event to be the correct.
This bug will only affect NFSv4.1 pnfs mounts and only when the server
does a layout recall callback, so it won't affect many. Without the patch,
a mount without the "pnfs" option will avoid the problem.
Found during testing of the pNFS server.
MFC after: 1 week
260785fe60