cxgb4: Add CLIP support to store compressed IPv6 address

The Compressed LIP region is used to hold a limited number of Local
IPv6 addresses.  This region is primarily used to reduce the TCAM
space consumed for an IPv6 offloaded connection.  A 128-bit LIP will
be reduced to 13-bit and stored in the TCAM if there is a match
between the IPv6 tuple's LIP and the one stored in the CLIP region.

Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>