net: microchip: vcap: Add tc flower keys for lan966x

Add the following TC flower filter keys to lan966x for IS2:
- ipv4_addr (sip and dip)
- ipv6_addr (sip and dip)
- control (IPv4 fragments)
- portnum (tcp and udp port numbers)
- basic (L3 and L4 protocol)
- vlan (outer vlan tag info)
- tcp (tcp flags)
- ip (tos field)

As the parsing of these keys is similar between lan966x and sparx5, move
the code in a separate file to be shared by these 2 chips. And put the
specific parsing outside of the common functions.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>