fix(icmp): fix check_icmpv6_name() to use correct IPv6 names

This was only called from IPSet.check_entry() to validate the input.
Also, some of the IPv4 names are the same as for IPv6. Overall, the
impact of this was probably low.

Fixes: 11567b7 ('New firewall.core.icmp providing names and types for icmp and icmpv6 values')
(cherry picked from commit d2fa474)

src/firewall/core/icmp.py

@@ -94,7 +94,7 @@ def check_icmp_type(_type):
     return False
 
 def check_icmpv6_name(_name):
-    if _name in ICMP_TYPES:
+    if _name in ICMPV6_TYPES:
         return True
     return False