src: proto: fixed a rreply symbol

src: proto: fixed a rreply symbol

There is a bug with rreply symbol. The rreply and reply symbol were the same.

There is a reproduction of this bug here:
$ sudo nft add rule arp art-t filter arp operation reply
$ sudo nft list table arp art-t
table arp art-t {
        chain filter {
		 type filter hook input priority 0;
                 arp operation 512
       	}
}

$ sudo nft add rule arp art-t filter arp operation rreply
$ sudo nft list table arp art-t
table arp art-t {
        chain filter {
		 type filter hook input priority 0;
                 arp operation 512  <=====
                 arp operation 512  <=====
       	}
}

Signed-off-by: Patrick McHardy <kaber@trash.net>