[PATCH] powerpc: Unify udbg (#2)

This patch unifies udbg for both ppc32 and ppc64 when building the
merged achitecture. xmon now has a single "back end". The powermac udbg
stuff gets enriched with some ADB capabilities and btext output. In
addition, the early_init callback is now called on ppc32 as well,
approx. in the same order as ppc64 regarding device-tree manipulations.
The init sequences of ppc32 and ppc64 are getting closer, I'll unify
them in a later patch.

For now, you can force udbg to the scc using "sccdbg" or to btext using
"btextdbg" on powermacs. I'll implement a cleaner way of forcing udbg
output to something else than the autodetected OF output device in a
later patch.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/powermac/pic.c

@@ -459,7 +459,7 @@ void __init pmac_pic_init(void)
 			mpic_setup_cascade(irqctrler2->intrs[0].line,
 					   pmac_u3_cascade, mpic2);
 		}
-#if defined(CONFIG_XMON) && defined(CONFIG_PPC32)
+#ifdef CONFIG_XMON
 		{
 			struct device_node* pswitch;
 			int nmi_irq;