tc: implement support for terse dump

tc: implement support for terse dump

Implement support for classifier/action terse dump using new TCA_DUMP_FLAGS
tlv with only available flag value TCA_DUMP_FLAGS_TERSE. Set the flag when
user requested it with following example CLI (-br for 'brief'):

$ tc -s -br filter show dev ens1f0 ingress
filter protocol ip pref 49151 flower chain 0
filter protocol ip pref 49151 flower chain 0 handle 0x1
  not_in_hw
        action order 1: gact    Action statistics:
        Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
        backlog 0b 0p requeues 0

filter protocol ip pref 49152 flower chain 0
filter protocol ip pref 49152 flower chain 0 handle 0x1
  not_in_hw
        action order 1: gact    Action statistics:
        Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
        backlog 0b 0p requeues 0

In terse mode dump only outputs essential data needed to identify the
filter and action (handle, cookie, etc.) and stats, if requested by the
user. The intention is to significantly improve rule dump rate by omitting
all static data that do not change after rule is created.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David Ahern <dsahern@gmail.com>