Merge branch 'prestera-route-offloading'

Yevhen Orlov says:

====================
net: marvell: prestera: add basic routes offloading

Add support for blackhole and local routes for Marvell Prestera driver.
Subscribe on fib notifications and handle add/del.

Add features:
 - Support route adding.
   e.g.: "ip route add blackhole 7.7.1.1/24"
   e.g.: "ip route add local 9.9.9.9 dev sw1p30"
 - Support "rt_trap", "rt_offload", "rt_offload_failed" flags
 - Handle case, when route in "local" table overlaps route in "main" table
   example:
        ip ro add blackhole 7.7.7.7
        ip ro add local 7.7.7.7 dev sw1p30
        # blackhole route will be deoffloaded. rt_offload flag disappeared

Limitations:
 - Only "blackhole" and "local" routes supported. "nexthop" routes is TRAP
   for now and will be implemented soon.
 - Only "local" and "main" tables supported
====================

Co-developed-by: Taras Chornyi <tchornyi@marvell.com>
Signed-off-by: Taras Chornyi <tchornyi@marvell.com>
Co-developed-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Signed-off-by: Yevhen Orlov <yevhen.orlov@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>