Make mouse wheel scrolling direction consistent between report and boot protocols.
Suggested by pavel.klinkovsky@gmail.com .

Reference: /n/sources/patch/applied/usbmouse-wheeldirection
Date: Sat Mar  2 12:10:30 CET 2013
Signed-off-by: miller@hamnavoe.com

--- /sys/src/cmd/usb/kb/kb.c	Sat Mar  2 12:07:50 2013
+++ /sys/src/cmd/usb/kb/kb.c	Sat Mar  2 12:07:47 2013
@@ -299,9 +299,9 @@
 	for(i = 0; i<sizeof buts; i++)
 		b |= (hidifcval(&kd->templ, KindButtons, i) & 1) << buts[i];
 	if(c > 3 && hidifcval(&kd->templ, KindWheel, 0) > 0)	/* up */
-		b |= 0x10;
-	if(c > 3 && hidifcval(&kd->templ, KindWheel, 0) < 0)	/* down */
 		b |= 0x08;
+	if(c > 3 && hidifcval(&kd->templ, KindWheel, 0) < 0)	/* down */
+		b |= 0x10;
 
 	*px = x;
 	*py = y;