pxa3xx_nand: remove hardcode irq number

Nand driver uses IRQ_NAND as hardcode irq number. In ARCH_MMP, the irq
number is different. So get irq resource from platform device structure
and use it in initialization and deinitialization code.

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>