powerpc/86xx: Add binding for LAWs and MCM

The first 4k region of CCSR space is well defined for local access
windows, CCSRBAR, etc.  The second 4k region is well defined as
register for configuring and getting errors for the MPX coherency
module.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

Documentation/powerpc/dts-bindings/fsl/mcm.txt

+=====================================================================
+MPX LAW & Coherency Module Device Tree Binding
+Copyright (C) 2009 Freescale Semiconductor Inc.
+=====================================================================
+
+Local Access Window (LAW) Node
+
+The LAW node represents the region of CCSR space where local access
+windows are configured.  For MCM based devices this is the first 4k
+of CCSR space that includes CCSRBAR, ALTCBAR, ALTCAR, BPTR, and some
+number of local access windows as specified by fsl,num-laws.
+
+PROPERTIES
+
+  - compatible
+      Usage: required
+      Value type: <string>
+      Definition: Must include "fsl,mcm-law"
+
+  - reg
+      Usage: required
+      Value type: <prop-encoded-array>
+      Definition: A standard property.  The value specifies the
+          physical address offset and length of the CCSR space
+          registers.
+
+  - fsl,num-laws
+      Usage: required
+      Value type: <u32>
+      Definition: The value specifies the number of local access
+          windows for this device.
+
+=====================================================================
+
+MPX Coherency Module Node
+
+The MPX LAW node represents the region of CCSR space where MCM config
+and error reporting registers exist, this is the second 4k (0x1000)
+of CCSR space.
+
+PROPERTIES
+
+  - compatible
+      Usage: required
+      Value type: <string>
+      Definition: Must include "fsl,CHIP-mcm", "fsl,mcm" where
+      CHIP is the processor (mpc8641, mpc8610, etc.)
+
+  - reg
+      Usage: required
+      Value type: <prop-encoded-array>
+      Definition: A standard property.  The value specifies the
+          physical address offset and length of the CCSR space
+          registers.
+
+   - interrupts
+      Usage: required
+      Value type: <prop-encoded-array>
+
+   - interrupt-parent
+      Usage: required
+      Value type: <phandle>
+
+=====================================================================