net: lan966x: Add TC filter chaining support for IS1 and IS2 VCAPs

Allow rules to be chained between IS1 VCAP and IS2 VCAP. Chaining
between IS1 lookups or between IS2 lookups are not supported by the
hardware.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>