Use assigned-clock properties to configure pllc4 as the parent clock
for sdmmc4 on Tegra210. pllc4 offers better jitter perfomance than
the default pllp and is required by HS200 and HS400 modes.
Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>