make shell math operations style more succulent

Convert the style:
	var=$((${var} + 1))
to:
	: $(( var += 1 ))

The latter is easier to read imo.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

init.d/keymaps.in

@@ -47,7 +47,7 @@ start()
 	n=1
 	while [ $n -le $ttyn ]; do
 		kbd_mode $kmode -C $ttydev$n
-		n=$(($n + 1))
+		: $(( n += 1 ))
 	done
 	eend 0