dt-bindings: rockchip-dw-mshc: use consistent clock names

The names of these clocks are "ciu-drive" and "ciu-sample" as described
for the clock-names property.  Avoid confusion by spelling these
correctly everywhere they are referenced.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Rob Herring <robh@kernel.org>