nfs: offer native ioctls even if CONFIG_COMPAT is set

Without this for example 64-bit binaries on typical amd64 distributions
would not be able to use ioctls on NFS.  For now this only affects clones.
Additionally ->compat_ioctl is defined even for non-compat builds, so
get rid of the pointless ifdef.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>