Input: xpad - fix report for dpad and inverted Y and RY axes on xbox 360

Make the driver report Y/RY up as positive value and down as negative. Also
make DPAD mapping the same as classic xpad.

Reported-by: Brian Magnuson <bdmagnuson@gmail.com>
Tested-by: Jan Kratochvil <honza@jikos.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>