USB: use DIV_ROUND_UP

The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
(d)) but is perhaps more readable.

An extract of the semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@haskernel@
@@

#include <linux/kernel.h>

@depends on haskernel@
expression n,d;
@@

(
- (n + d - 1) / d
+ DIV_ROUND_UP(n,d)
|
- (n + (d - 1)) / d
+ DIV_ROUND_UP(n,d)
)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP((n),d)
+ DIV_ROUND_UP(n,d)

@depends on haskernel@
expression n,d;
@@

- DIV_ROUND_UP(n,(d))
+ DIV_ROUND_UP(n,d)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/misc/usbtest.c

@@ -1404,7 +1404,7 @@ static struct urb *iso_alloc_urb (
 		return NULL;
 	maxp = 0x7ff & le16_to_cpu(desc->wMaxPacketSize);
 	maxp *= 1 + (0x3 & (le16_to_cpu(desc->wMaxPacketSize) >> 11));
-	packets = (bytes + maxp - 1) / maxp;
+	packets = DIV_ROUND_UP(bytes, maxp);
 
 	urb = usb_alloc_urb (packets, GFP_KERNEL);
 	if (!urb)