usb: wusbcore: set packet count correctly on isoc transfers

This patch correctly sets the dwNumOfPackets field of the HWA transfer
request for isochronous transfers with multiple segments.  Previously
all segments used the value that was set for the first segment which may
not be correct.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>