[ARM] 4435/1: PXA: remove PXA_INTERNAL_IRQS

1. define PXA_GPIO_IRQ_BASE to be right after the internal IRQs,
   and define PXA_GPIO_IRQ_NUM to be 128 for all PXA2xx variants

2. make the code specific to the high IRQ numbers (32..64) to be
   PXA27x specific

3. add a function pxa_init_irq_high() to initialize the internal
   high IRQ chip, the invoke of this function could be moved to
   PXA27x specific initialization code

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>