[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>

Documentation/powerpc/booting-without-of.txt

@@ -719,6 +719,11 @@ address which can extend beyond that limit.
     - model : this is your board name/model
     - #address-cells : address representation for "root" devices
     - #size-cells: the size representation for "root" devices
+    - device_type : This property shouldn't be necessary. However, if
+      you decide to create a device_type for your root node, make sure it
+      is _not_ "chrp" unless your platform is a pSeries or PAPR compliant
+      one for 64-bit, or a CHRP-type machine for 32-bit as this will
+      matched by the kernel this way.
 
   Additionally, some recommended properties are: