rxrpc: rxkad: Remove redundant variable offset

Variable offset is being assigned a value from a calculation
however the variable is never read, so this redundant variable
can be removed.

Cleans up the following clang-analyzer warning:

net/rxrpc/rxkad.c:579:2: warning: Value stored to 'offset' is never read
[clang-analyzer-deadcode.DeadStores].

net/rxrpc/rxkad.c:485:2: warning: Value stored to 'offset' is never read
[clang-analyzer-deadcode.DeadStores].
Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NJiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/rxrpc/rxkad.c

@@ -482,7 +482,6 @@ static int rxkad_verify_packet_1(struct rxrpc_call *call, struct sk_buff *skb,
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
-	offset += sizeof(sechdr);
 	len -= sizeof(sechdr);
 
 	buf = ntohl(sechdr.data_size);
@@ -576,7 +575,6 @@ static int rxkad_verify_packet_2(struct rxrpc_call *call, struct sk_buff *skb,
 					     RXKADDATALEN);
 		goto protocol_error;
 	}
-	offset += sizeof(sechdr);
 	len -= sizeof(sechdr);
 
 	buf = ntohl(sechdr.data_size);