sdhci_fsl_fdt.c: Add a missing call to mmc_fdt_parse.

[lha_semihalf.com]

Summary

Add a missing call to mmc_fdt_parse, without it some dts properties
are not parsed.

[manu]

Now they are parsed but you don't use them.
See https://cgit.freebsd.org/src/commit/sys/arm/allwinner/aw_mmc.c?id=9ed8321078444aea2a90a361f91e54065d5daf21 for how to use it.

[lha_semihalf.com]

You are right, I am working on using parsed values and will update this patch next week probably.

[lha_semihalf.com]

Implement usage of values parsed from fdt, add support for max-frequency property.