netdev/ipv6: Move xxx_ipv6multicast from arch to common code

The `xxx_ipv6multicast` function in each driver is not adapted to
multiple IPv6 addresses yet, and they're redundant, so try to take them
into common code.

Change:
1. Add MAC `g_ipv6_ethallnodes` and `g_ipv6_ethallrouters` in
   `icmpv6_devinit` and call them in `netdev_register`
2. Add multicast MAC for Neighbor Solicitation when adding any IPv6
   address, and remove them when IPv6 address is removed
3. Select `NET_MCASTGROUP` when `NET_ICMPv6` because now we need
   `d_addmac` when we have ICMPv6

Note:
We want modules outside net stack to call functions like
`netdev_ipv6_add` and never touch the related MAC address, so these MAC
functions are added as internal functions to `net/netdev/netdev.h`

Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>

net/netdev/netdev_register.c

@@ -40,6 +40,7 @@
 #include <nuttx/net/can.h>
 
 #include "utils/utils.h"
+#include "icmpv6/icmpv6.h"
 #include "igmp/igmp.h"
 #include "mld/mld.h"
 #include "netdev/netdev.h"
@@ -475,6 +476,12 @@ int netdev_register(FAR struct net_driver_s *dev, enum net_lltype_e lltype)
       mld_devinit(dev);
 #endif
 
+#ifdef NET_ICMPv6_HAVE_STACK
+      /* Configure the device for ICMPv6 support */
+
+      icmpv6_devinit(dev);
+#endif
+
       net_unlock();
 
 #if defined(CONFIG_NET_ETHERNET) || defined(CONFIG_DRIVERS_IEEE80211)