ss: remove non-functional slabinfo

ss: remove non-functional slabinfo

Ss was using slabinfo to try and intuit TCP statistics.
The slabinfo changed several times since 2.4 and all these statistics
are broken by renames and slab merging. Plus slabinfo does not exist
at all if kernel is compiled with SLUB option.

Rather than trying to fix kernel, just trim away the no longer
valid statistics.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>