[PATCH] USB: ftdi_sio: Update RTS and DTR simultaneously

ftdi_sio: Update RTS and DTR simultaneously, using a single control URB
instead of separate control URBs for RTS and DTR.  Reinhard Bergmann
observed time differences of up to 680 ms with his application on a
2.4.22 kernel when RTS and DTR were updated using separate control
URBs, which is unacceptable.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>