Remove hold_packets attribute from DNSRRCountField

DNSRRCountField is a counter for DNSRRField fields and do not hold packets.

--HG--
branch : issue-5105

scapy/layers/dns.py

@@ -52,7 +52,6 @@ class DNSStrField(StrField):
 
 
 class DNSRRCountField(ShortField):
-    holds_packets=1
     def __init__(self, name, default, rr):
         ShortField.__init__(self, name, default)
         self.rr = rr