[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/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index 6c3989f6..ada50aa 100644
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -160,7 +160,7 @@
 	case IOC_NVRAM_GET_OFFSET: {
 		int part, offset;
 
-		if (_machine != PLATFORM_POWERMAC)
+		if (!machine_is(powermac))
 			return -EINVAL;
 		if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
 			return -EFAULT;
@@ -444,7 +444,7 @@
 	 * in our nvram, as Apple defined partitions use pretty much
 	 * all of the space
 	 */
-	if (_machine == PLATFORM_POWERMAC)
+	if (machine_is(powermac))
 		return -ENOSPC;
 
 	/* see if we have an OS partition that meets our needs.