inet: properly align icsk_ca_priv

tcp_illinois and upcoming tcp_cdg require 64bit alignment of
icsk_ca_priv

x86 does not care, but other architectures might.

Fixes: 05cbc0db ("ipv4: Create probe timer for tcp PMTU as per RFC4821")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Fan Du <fan.du@intel.com>
Acked-by: NFan Du <fan.du@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/inet_connection_sock.h

@@ -129,9 +129,10 @@ struct inet_connection_sock {
 
 		u32		  probe_timestamp;
 	} icsk_mtup;
-	u32			  icsk_ca_priv[16];
 	u32			  icsk_user_timeout;
-#define ICSK_CA_PRIV_SIZE	(16 * sizeof(u32))
+
+	u64			  icsk_ca_priv[64 / sizeof(u64)];
+#define ICSK_CA_PRIV_SIZE      (8 * sizeof(u64))
 };
 
 #define ICSK_TIME_RETRANS	1	/* Retransmit timer */