mmc: sdhci-pxav2: change clock name to match DT bindings

mmc: sdhci-pxav2: change clock name to match DT bindings

The devicetree bindings for this driver specify that the two allowed
clock names are io and core. Change this driver to look for io, but
allow any name if it fails for backwards compatibility. Follow the same
pattern used in sdhci-pxav3, but add support for EPROBE_DEFER.

Get rid of an unnecessary pdev->dev while we're at it.

Signed-off-by: Doug Brown <doug@schmorgal.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20230116194401.20372-5-doug@schmorgal.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>