net: marvell: prestera: Add length macros for prestera_ip_addr

Add macros to determine IP address length (internal driver types).
This will be used in next patches for nexthops logic.
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: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/prestera/prestera_router_hw.h

@@ -31,6 +31,8 @@ struct prestera_ip_addr {
 		PRESTERA_IPV4 = 0,
 		PRESTERA_IPV6
 	} v;
+#define PRESTERA_IP_ADDR_PLEN(V) ((V) == PRESTERA_IPV4 ? 32 : \
+				  /* (V) == PRESTERA_IPV6 ? */ 128 /* : 0 */)
 };
 
 struct prestera_nh_neigh_key {