MAINTAINERS: Update git repo for Renesas clock drivers

Align the clock branch name with other renesas-* branches pulled by
subsystem maintainers.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20200925110713.2652-1-geert+renesas@glider.be

MAINTAINERS

@@ -14888,7 +14888,7 @@ RENESAS CLOCK DRIVERS
 M:	Geert Uytterhoeven <geert+renesas@glider.be>
 L:	linux-renesas-soc@vger.kernel.org
 S:	Supported
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git clk-renesas
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git renesas-clk
 F:	Documentation/devicetree/bindings/clock/renesas,*
 F:	drivers/clk/renesas/