gpio: pxa: remove mach IRQ includes

In preparation to enable ARCH_MMP on ARM64, the include of mach/irqs.h
must be eliminated. mach/irqs.h was being included for IRQ_GPIO{0,1},
but these IRQs are always passed in as resources now. We can use irq0
and irq1 and get rid of IRQ_GPIOx. Get rid of the ifdef in the process
as it is no longer needed.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>