[nuttx] Type mismatch in icmpv6.h

[SP [e-mail] [nuttx]]

We got these errors:

~~~
icmpv6/icmpv6_rnotify.c: In function 'icmpv6_rwait_setup':
icmpv6/icmpv6_rnotify.c:180:21: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
notify->rn_flink = g_icmpv6_rwaiters;
^
icmpv6/icmpv6_rnotify.c: In function 'icmpv6_rwait_cancel':
icmpv6/icmpv6_rnotify.c:215:26: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
prev = curr, curr = curr->rn_flink);
^
icmpv6/icmpv6_rnotify.c:226:29: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
g_icmpv6_rwaiters = notify->rn_flink;
^
icmpv6/icmpv6_rnotify.c: In function 'icmpv6_rnotify':
icmpv6/icmpv6_rnotify.c:320:45: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
for (curr = g_icmpv6_rwaiters; curr; curr = curr->rn_flink)
~~~

I think the patch attached fixes this issue. It's for 7.23.