dt-bindings: clock: renesas: cpg-mssr: Fix r8a774b1 typo

This patch fixes the typo %s/r8a774a1/r8a774b1/.

Fixes: 10003938 ("dt-bindings: clock: renesas: cpg-mssr: Document r8a774b1 binding")
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Link: https://lore.kernel.org/r/1576673984-37752-1-git-send-email-biju.das@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

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

@@ -19,7 +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,r8a774b1-cpg-mssr" for the r8a774b1 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)