[media] mceusb: Optimize DIV_ROUND_CLOSEST call

DIV_ROUND_CLOSEST is faster if the compiler knows it will only be
dealing with unsigned dividends.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>