[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/mm/init_32.c

@@ -188,6 +188,11 @@ void __init MMU_init(void)
 
 	if (ppc_md.progress)
 		ppc_md.progress("MMU:exit", 0x211);
+
+	/* From now on, btext is no longer BAT mapped if it was at all */
+#ifdef CONFIG_BOOTX_TEXT
+	btext_unmap();
+#endif
 }
 
 /* This is only called until mem_init is done. */