nfscl: Fix two more cases for forced dismount

Although I was not able to cause a failure during testing, there
are places in nfscl_removedeleg() and nfscl_renamedeleg() where
I think a forced dismount could get hung. This patch fixes those.

This patch only affects forced dismount and only if the NFSv4
server is issuing delegations to the client.

Found by code inspection.

MFC after: 2 weeks