powerpc/irqdomain: Fix broken NR_IRQ references

The switch from using irq_map to irq_alloc_desc*() for managing irq
number allocations introduced new bugs in some of the powerpc
interrupt code.  Several functions rely on the value of NR_IRQS to
determine the maximum irq number that could get allocated.  However,
with sparse_irq and using irq_alloc_desc*() the maximum possible irq
number is now specified with 'nr_irqs' which may be a number larger
than NR_IRQS.  This has caused breakage on powermac when
CONFIG_NR_IRQS is set to 32.

This patch removes most of the direct references to NR_IRQS in the
powerpc code and replaces them with either a nr_irqs reference or by
using the common for_each_irq_desc() macro.  The powerpc-specific
for_each_irq() macro is removed at the same time.

Also, the Cell axon_msi driver is refactored to remove the global
build assumption on the size of NR_IRQS and instead add a limit to the
maximum irq number when calling irq_domain_add_nomap().

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/sysdev/cpm2_pic.c b/arch/powerpc/sysdev/cpm2_pic.c
index d3be961..10386b6 100644
--- a/arch/powerpc/sysdev/cpm2_pic.c
+++ b/arch/powerpc/sysdev/cpm2_pic.c
@@ -51,8 +51,7 @@
 static intctl_cpm2_t __iomem *cpm2_intctl;
 
 static struct irq_domain *cpm2_pic_host;
-#define NR_MASK_WORDS   ((NR_IRQS + 31) / 32)
-static unsigned long ppc_cached_irq_mask[NR_MASK_WORDS];
+static unsigned long ppc_cached_irq_mask[2]; /* 2 32-bit registers */
 
 static const u_char irq_to_siureg[] = {
 	1, 1, 1, 1, 1, 1, 1, 1,