* ARM PrimeCell MultiMedia Card Interface (MMCI) PL180/1

The ARM PrimeCell MMCI PL180 and PL181 provides and interface for
reading and writing to MultiMedia and SD cards alike.

Required properties:
- compatible             : contains "arm,pl18x", "arm,primecell".
- reg                    : contains pl18x registers and length.
- interrupts             : contains the device IRQ(s).
- arm,primecell-periphid : contains the PrimeCell Peripheral ID.

Optional properties:
- wp-gpios               : contains any write protect (ro) gpios
- cd-gpios               : contains any card detection gpios
- cd-inverted            : indicates whether the cd gpio is inverted
- max-frequency          : contains the maximum operating frequency
- bus-width              : number of data lines, can be <1>, <4>, or <8>
- mmc-cap-mmc-highspeed  : indicates whether MMC is high speed capable
- mmc-cap-sd-highspeed   : indicates whether SD is high speed capable
