clk: shmobile: r8a7794: Document DIV6 clock bindings

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Documentation/devicetree/bindings/clock/renesas,cpg-div6-clocks.txt

@@ -12,6 +12,7 @@ Required Properties:
     - "renesas,r8a7790-div6-clock" for R8A7790 (R-Car H2) DIV6 clocks
     - "renesas,r8a7791-div6-clock" for R8A7791 (R-Car M2-W) DIV6 clocks
     - "renesas,r8a7793-div6-clock" for R8A7793 (R-Car M2-N) DIV6 clocks
+    - "renesas,r8a7794-div6-clock" for R8A7794 (R-Car E2) DIV6 clocks
     - "renesas,sh73a0-div6-clock" for SH73A0 (SH-Mobile AG5) DIV6 clocks
     - "renesas,cpg-div6-clock" for generic DIV6 clocks
   - reg: Base address and length of the memory resource used by the DIV6 clock