mmc: sdhci-omap: Handle voltages to add support omap4

mmc: sdhci-omap: Handle voltages to add support omap4

In order to start deprecating the custom omap_hsmmc.c in favor of the
generic sdhci-omap driver, we need to add support for voltages for earlier
SoCs.

The PBIAS regulator on omap4 and earlier only supports nominal values of
1.8V and 3.0V, while omap5 and later support nominal values of 1.8V and
3.3V IO voltage.

This gets omap4/5 working with sdhci-omap driver.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20211015104720.52240-3-tony@atomide.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>