On certain boards not all GPIOs may be used as wakeup sources, in which
case some of enable_irq_wake() calls will fail. On resume calling
disable_irq_wake() will warn about unbalanced IRQ wake disable.

Solve this by checking whether enable_irq_wake() succeeded or not and
no not call disable_irq_wake() for these GPIOs/IRQs that have not been
enabled.
Reported-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>