[PATCH] rt2x00: Increase rt2x00usb_vendor_request timeout.

By increasing the timeout for rt2x00usb_vendor_request,
we should limit the number of loops required to send
a signal to the device succefully.
500ms timeout is specified by the Ralink legacy drivers
for rt2500usb. For rt73usb 1000ms is specified, but that
includes the timeout for the firmware which is already
specified in a different define.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>