Add support for the controller present on the AM62x SoC.

There are instances:
sdhci0: 8bit bus width, max 200 MBps
sdhci1: 4bit bus width, max 100 MBps
sdhci2: 4bit bus width, max 100 MBps

The PHY used for 8 bit instance is same as the PHY for the 4 bit instance.
Therefore, introduce a new bus width independent compatible for AM62 SoC
that uses the driver data required for 4 bit instance.
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20220218072840.5629-1-a-govindraju@ti.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>