dt-bindings: clock: renesas: cpg-mssr: Document r8a774b1 binding

Add binding documentation for the RZ/G2N (R8A774b1) Clock Pulse
Generator driver.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Link: https://lore.kernel.org/r/1568881036-4404-6-git-send-email-biju.das@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt

@@ -19,6 +19,7 @@ Required Properties:
       - "renesas,r8a7745-cpg-mssr" for the r8a7745 SoC (RZ/G1E)
       - "renesas,r8a77470-cpg-mssr" for the r8a77470 SoC (RZ/G1C)
       - "renesas,r8a774a1-cpg-mssr" for the r8a774a1 SoC (RZ/G2M)
+      - "renesas,r8a774b1-cpg-mssr" for the r8a774a1 SoC (RZ/G2N)
       - "renesas,r8a774c0-cpg-mssr" for the r8a774c0 SoC (RZ/G2E)
       - "renesas,r8a7790-cpg-mssr" for the r8a7790 SoC (R-Car H2)
       - "renesas,r8a7791-cpg-mssr" for the r8a7791 SoC (R-Car M2-W)
@@ -40,10 +41,11 @@ Required Properties:
     clock-names
   - clock-names: List of external parent clock names. Valid names are:
       - "extal" (r7s9210, r8a7743, r8a7744, r8a7745, r8a77470, r8a774a1,
-		 r8a774c0, r8a7790, r8a7791, r8a7792, r8a7793, r8a7794,
-		 r8a7795, r8a7796, r8a77965, r8a77970, r8a77980, r8a77990,
-		 r8a77995)
-      - "extalr" (r8a774a1, r8a7795, r8a7796, r8a77965, r8a77970, r8a77980)
+		 r8a774b1, r8a774c0, r8a7790, r8a7791, r8a7792, r8a7793,
+		 r8a7794, r8a7795, r8a7796, r8a77965, r8a77970, r8a77980,
+		 r8a77990, r8a77995)
+      - "extalr" (r8a774a1, r8a774b1, r8a7795, r8a7796, r8a77965, r8a77970,
+		  r8a77980)
       - "usb_extal" (r8a7743, r8a7744, r8a7745, r8a77470, r8a7790, r8a7791,
 		     r8a7793, r8a7794)