sys/mount.h: restore KNF_NOKQLOCK in VFS_KNOTE_{,UN}LOCKED() call to KNOTE()

ZFS needs to take internal sleepable lock in its implementation of
VOP_GETATTR(). Due to this, kq must be unlocked around calls to the vfs
filter methods.

Fixes: 1d5e4020e36e ("vnode: add VIRF_KNOTE flag")
Reported and tested by: des
Sponsored by: The FreeBSD Foundation
MFC after: 1 week