dt-bindings: timer: renesas, cmt: Add CMT0234 to sh73a0 and r8a7740

Document the on-chip CMT devices included in r8a7740 and sh73a0.

Included in this patch is DT binding documentation for 32-bit CMTs
CMT0, CMT2, CMT3 and CMT4. They all contain a single channel and are
quite similar however some minor differences still exist:
 - "Counter input clock" (clock input and on-device divider)
    One example is that RCLK 1/1 is supported by CMT2, CMT3 and CMT4.
 - "Wakeup request" (supported by CMT0 and CMT2)

Because of this one unique compat string per CMT device is selected.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Documentation/devicetree/bindings/timer/renesas,cmt.txt

@@ -22,6 +22,10 @@ Required Properties:
 
     - "renesas,r8a73a4-cmt0" for the 32-bit CMT0 device included in r8a73a4.
     - "renesas,r8a73a4-cmt1" for the 48-bit CMT1 device included in r8a73a4.
+    - "renesas,r8a7740-cmt0" for the 32-bit CMT0 device included in r8a7740.
+    - "renesas,r8a7740-cmt2" for the 32-bit CMT2 device included in r8a7740.
+    - "renesas,r8a7740-cmt3" for the 32-bit CMT3 device included in r8a7740.
+    - "renesas,r8a7740-cmt4" for the 32-bit CMT4 device included in r8a7740.
     - "renesas,r8a7743-cmt0" for the 32-bit CMT0 device included in r8a7743.
     - "renesas,r8a7743-cmt1" for the 48-bit CMT1 device included in r8a7743.
     - "renesas,r8a7744-cmt0" for the 32-bit CMT0 device included in r8a7744.
@@ -54,6 +58,10 @@ Required Properties:
     - "renesas,r8a77980-cmt1" for the 48-bit CMT1 device included in r8a77980.
     - "renesas,r8a77990-cmt0" for the 32-bit CMT0 device included in r8a77990.
     - "renesas,r8a77990-cmt1" for the 48-bit CMT1 device included in r8a77990.
+    - "renesas,sh73a0-cmt0" for the 32-bit CMT0 device included in sh73a0.
+    - "renesas,sh73a0-cmt2" for the 32-bit CMT2 device included in sh73a0.
+    - "renesas,sh73a0-cmt3" for the 32-bit CMT3 device included in sh73a0.
+    - "renesas,sh73a0-cmt4" for the 32-bit CMT4 device included in sh73a0.
 
     - "renesas,rcar-gen2-cmt0" for 32-bit CMT0 devices included in R-Car Gen2
 		and RZ/G1.