net/tls: move definition of tls ops into net/tls.h

There seems to be no reason for tls_ops to be defined in netdevice.h
which is included in a lot of places.  Don't wrap the struct/enum
declaration in ifdefs, it trickles down unnecessary ifdefs into
driver code.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>