USB: increase usbdevfs max isoc buffer size

The current limit only allows isochronous transfers up to 32kbyte/urb,
updating this to 192 kbyte/urb improves the reliability of the
transfer. USB 2.0 transfer is possible with 32kbyte but increases the
chance of corrupted/incomplete data when the system is performing some
other tasks in the background.

http://www.spinics.net/lists/linux-usb/msg19955.html

Signed-off-by: Markus Rechberger <mrechberger@gmail.com>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>