rp2: Remove redundant IPv6 configuration.

IPv6 settings are now defined in the common LWIP configuration:
- LWIP_IPV6 is enabled by default in lwipopts_common.h
- LWIP_ND6_NUM_DESTINATIONS is set to 4 in lwipopts_common.h
- LWIP_ND6_QUEUEING is set to 0 in lwipopts_common.h

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

ports/rp2/lwip_inc/lwipopts.h

@@ -5,9 +5,6 @@
 #define LWIP_NETIF_STATUS_CALLBACK      1
 
 #define LWIP_IPV4                       1
-#define LWIP_IPV6                       1
-#define LWIP_ND6_NUM_DESTINATIONS       4
-#define LWIP_ND6_QUEUEING               0
 
 #define LWIP_RAND() rosc_random_u32()