ARM: shmobile: r8a7794: document MSTP clock support

Signed-off-by: NUlrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: NMike Turquette <mturquette@linaro.org>

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

@@ -14,6 +14,7 @@ Required Properties:
     - "renesas,r8a7779-mstp-clocks" for R8A7779 (R-Car H1) MSTP gate clocks
     - "renesas,r8a7790-mstp-clocks" for R8A7790 (R-Car H2) MSTP gate clocks
     - "renesas,r8a7791-mstp-clocks" for R8A7791 (R-Car M2) MSTP gate clocks
+    - "renesas,r8a7794-mstp-clocks" for R8A7794 (R-Car E2) MSTP gate clocks
     - "renesas,cpg-mstp-clock" for generic MSTP gate clocks
   - reg: Base address and length of the I/O mapped registers used by the MSTP
     clocks. The first register is the clock control register and is mandatory.