[IPV4] inetpeer: Get rid of volatile from peer_total

The variable peer_total is protected by a lock.  The volatile marker
makes no sense.  This shaves off 20 bytes on i386.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>