MAINTAINERS: Add Marvell mvebu clock drivers

drivers/clk/mvebu/ is missing a maintainers entry. Add it to the
existing entry for the Marvell mvebu platforms.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230327-mvebu-clk-fixes-v2-1-8333729ee45d@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: robherring

MAINTAINERS

@@ -2364,6 +2364,7 @@ F:	arch/arm/configs/mvebu_*_defconfig
 F:	arch/arm/mach-mvebu/
 F:	arch/arm64/boot/dts/marvell/armada*
 F:	arch/arm64/boot/dts/marvell/cn913*
+F:	drivers/clk/mvebu/
 F:	drivers/cpufreq/armada-37xx-cpufreq.c
 F:	drivers/cpufreq/armada-8k-cpufreq.c
 F:	drivers/cpufreq/mvebu-cpufreq.c