IRQ_USB was implicitly included by gpio.h. Use the existing variable
instead of IRQ_USB.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Acked-by: NEric Miao <eric.y.miao@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>