[ARM] pxa: fix interrupts number calculation when CONFIG_PXA_HAVE_ISA_IRQS=y
[ARM] pxa: fix interrupts number calculation when CONFIG_PXA_HAVE_ISA_IRQS=y

Commit d2c37068429b29d6549cf3486fc84b836689e122 ([ARM] pxa:
initialize default interrupt priority and use ICHP for IRQ handling)
broke ISA interrupt support on pxa27x/3xx.

In such a case, PXA_IRQ(0) != 0, and the IRQ number computed from
ICHP must be offset by PXA_IRQ(0).

Tested on an Arcom Zeus (pxa270), with both CONFIG_PXA_HAVE_ISA_IRQS
enabled and disabled.

Signed-off-by: Marc Zyngier <f0ee73f698464d9b24960cfd983e278ecc504ba8@misterjones.org>
Tested-by: Haojian Zhuang <979139d45d262f0480136b0da512e0afa0fe79d3@marvell.com>
Signed-off-by: Eric Miao <60e376623d7bcedd53f4c51cbb2c060fb40a4887@gmail.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs