arm64: dts: tegra186: Assign clocks for sdmmc1 and sdmmc4

Configure sdmmc4 parent clock to pllc4 and sdmmc1 to pllp_out0 by
setting the assigned-clocks device tree properties. pllc4 offer
better jitter performance and should be used with higher speed
modes like HS200 and HS400.

Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>