Input: ads7846 - do not attempt IRQ workaround when deferring probe

When request_irq() returns -EPORBE_DEFER we should abort probe and try
again later instead of trying to engage IRQ trigger workaround.

Link: https://lore.kernel.org/r/20210910045039.4020199-3-dmitry.torokhov@gmail.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>