Added support in tc flower for filtering based on port ranges.

Example:
1. Match on a port range:
-------------------------
$ tc filter add dev enp4s0 protocol ip parent ffff:\
  prio 1 flower ip_proto tcp dst_port range 20-30 skip_hw\
  action drop

$ tc -s filter show dev enp4s0 parent ffff:
filter protocol ip pref 1 flower chain 0
filter protocol ip pref 1 flower chain 0 handle 0x1
  eth_type ipv4
  ip_proto tcp
  dst_port range 20-30
  skip_hw
  not_in_hw
        action order 1: gact action drop
         random type none pass val 0
         index 1 ref 1 bind 1 installed 85 sec used 3 sec
        Action statistics:
        Sent 460 bytes 10 pkt (dropped 10, overlimits 0 requeues 0)
        backlog 0b 0p requeues 0

2. Match on IP address and port range:
--------------------------------------
$ tc filter add dev enp4s0 protocol ip parent ffff:\
  prio 1 flower dst_ip 192.168.1.1 ip_proto tcp dst_port range 100-200\
  skip_hw action drop

$ tc -s filter show dev enp4s0 parent ffff:
filter protocol ip pref 1 flower chain 0 handle 0x2
  eth_type ipv4
  ip_proto tcp
  dst_ip 192.168.1.1
  dst_port range 100-200
  skip_hw
  not_in_hw
        action order 1: gact action drop
         random type none pass val 0
         index 2 ref 1 bind 1 installed 58 sec used 2 sec
        Action statistics:
        Sent 920 bytes 20 pkt (dropped 20, overlimits 0 requeues 0)
        backlog 0b 0p requeues 0

v4:
1. Added condition before setting port key.
2. Organized setting and dumping port range keys into functions
   and added validation of input range.

v3:
1. Moved new fields in UAPI enum to the end of enum.
2. Removed couple of empty lines.

v2:
Addressed Jiri's comments:
1. Added separate functions for dst and src comparisons.
2. Removed endpoint enum.
3. Added new bit TCA_FLOWER_FLAGS_RANGE to decide normal/range
  lookup.
4. Cleaned up fl_lookup function.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>

Signed-off-by: David S. Miller <davem@davemloft.net>