arm64: dts: rockchip: Fix DWMMC clocks

Trying to boot an RK3328 box with an HS200-capable eMMC, I see said eMMC
fail to initialise as it can't run its tuning procedure, because the
sample clock is missing. Upon closer inspection, whilst the clock is
present in the DT, its name is subtly incorrect per the binding, so
__of_clk_get_by_name() never finds it. By inspection, the drive clock
suffers from a similar problem, so has never worked properly either.

Fix up all instances of the incorrect clock names across the 64-bit DTs.

Fixes: d717f735 ("arm64: dts: rockchip: add sdmmc/sdio/emmc nodes for RK3328 SoCs")
Fixes: b790c2ca

 ("arm64: dts: add Rockchip rk3368 core dtsi and board dts for the r88 board")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>