thermal: rcar: Document SoC-specific bindings

The documentation only mentioned the generic fallback compatible property.
Add the missing SoC-specific compatible properties, some of which are
already in use.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <eduardo.valentin@ti.com>
Cc: linux-pm@vger.kernel.org
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

Documentation/devicetree/bindings/thermal/rcar-thermal.txt

 * Renesas R-Car Thermal
 
 Required properties:
-- compatible		: "renesas,rcar-thermal"
+- compatible		: "renesas,thermal-<soctype>", "renesas,rcar-thermal"
+			  as fallback.
+			  Examples with soctypes are:
+			    - "renesas,thermal-r8a73a4" (R-Mobile AP6)
+			    - "renesas,thermal-r8a7779" (R-Car H1)
+			    - "renesas,thermal-r8a7790" (R-Car H2)
+			    - "renesas,thermal-r8a7791" (R-Car M2)
 - reg			: Address range of the thermal registers.
 			  The 1st reg will be recognized as common register
 			  if it has "interrupts".
@@ -12,18 +18,18 @@ Option properties:
 
 Example (non interrupt support):
 
-thermal@e61f0100 {
-	compatible = "renesas,rcar-thermal";
-	reg = <0xe61f0100 0x38>;
+thermal@ffc48000 {
+	compatible = "renesas,thermal-r8a7779", "renesas,rcar-thermal";
+	reg = <0xffc48000 0x38>;
 };
 
 Example (interrupt support):
 
 thermal@e61f0000 {
-	compatible = "renesas,rcar-thermal";
+	compatible = "renesas,thermal-r8a73a4", "renesas,rcar-thermal";
 	reg = <0xe61f0000 0x14
 		0xe61f0100 0x38
 		0xe61f0200 0x38
 		0xe61f0300 0x38>;
-	interrupts = <0 69 4>;
+	interrupts = <0 69 IRQ_TYPE_LEVEL_HIGH>;
 };