mmc: exynos_dw_mmc: add support for SD UHS mode

mmc: exynos_dw_mmc: add support for SD UHS mode

SD UHS mode is already supported by the Exynos DW-MMC driver in mainline
Linux. Using that as reference, add support in the U-Boot driver.

The maximum frequency was capped to 200000000, increase it to 208000000,
which is the required frequency for UHS_SDR104, which has the highest
frequency of all UHS modes. Moreover, add UHS_CAPS to host capailities.
These changes allow both host and card to recognize support for all UHS
modes.

SDR104, SDR50, and DDR50 have their own CLKSEL timing values, which
requires the CIU div value to be set in bits 18:16. Move the function
exynos_dwmci_clksel() below exynos_dwmmc_get_ciu_div() so that the
latter is accessible from the former, and add cases for said timing
modes.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>