Make the Altera JTAG UART device driver slightly more forgiving of

the foibles of a sub-par hrdware interface by increasing the timeout
for spotting JTAG polling from one to two seconds.

sys/dev/altera/jtag_uart/altera_jtag_uart_tty.c

@@ -67,7 +67,7 @@ static struct ttydevsw aju_ttydevsw = {
  * When polling for the AC bit, the number of times we have to not see it
  * before assuming JTAG has disappeared on us.  By default, one second.
  */
-#define	AJU_JTAG_MAXMISS		5
+#define	AJU_JTAG_MAXMISS		10
 
 /*
  * Polling intervals for input/output and JTAG connection events.