tcp: Update TCP_BASE_MSS comment

TCP_BASE_MSS is used as the default initial MSS value when MTU probing is
enabled. Update the comment to reflect this.
Suggested-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NJosh Hunt <johunt@akamai.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Acked-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/tcp.h

@@ -64,7 +64,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */
 #define TCP_MIN_MSS		88U
 
-/* The least MTU to use for probing */
+/* The initial MTU to use for probing */
 #define TCP_BASE_MSS		1024
 
 /* probing interval, default to 10 minutes as per RFC4821 */