[PATCH] powerpc: Kill _machine and hard-coded platform numbers

This removes statically assigned platform numbers and reworks the
powerpc platform probe code to use a better mechanism.  With this,
board support files can simply declare a new machine type with a
macro, and implement a probe() function that uses the flattened
device-tree to detect if they apply for a given machine.

We now have a machine_is() macro that replaces the comparisons of
_machine with the various PLATFORM_* constants.  This commit also
changes various drivers to use the new macro instead of looking at
_machine.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/sound/ppc/pmac.c b/sound/ppc/pmac.c
index aa57170..f0794ef 100644
--- a/sound/ppc/pmac.c
+++ b/sound/ppc/pmac.c
@@ -869,7 +869,7 @@
 
 	u32 layout_id = 0;
 
-	if (_machine != _MACH_Pmac)
+	if (!machine_is(powermac))
 		return -ENODEV;
 
 	chip->subframe = 0;