[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/arch/powerpc/platforms/powermac/nvram.c b/arch/powerpc/platforms/powermac/nvram.c
index 3aa3477..262f967 100644
--- a/arch/powerpc/platforms/powermac/nvram.c
+++ b/arch/powerpc/platforms/powermac/nvram.c
@@ -597,7 +597,7 @@
 	}
 
 #ifdef CONFIG_PPC32
-	if (_machine == _MACH_chrp && nvram_naddrs == 1) {
+	if (machine_is(chrp) && nvram_naddrs == 1) {
 		nvram_data = ioremap(r1.start, s1);
 		nvram_mult = 1;
 		ppc_md.nvram_read_val	= direct_nvram_read_byte;