hw/sd/sdhci: Support big endian SD host controller interfaces

hw/sd/sdhci: Support big endian SD host controller interfaces

Some SDHCI IP can be synthetized in various endianness:
https://github.com/u-boot/u-boot/blob/v2021.04/doc/README.fsl-esdhc

 - CONFIG_SYS_FSL_ESDHC_BE

   ESDHC IP is in big-endian mode. Accessing ESDHC registers can be
   determined by ESDHC IP's endian mode or processor's endian mode.

Our current implementation is little-endian. In order to support
big endianness:

- Rename current MemoryRegionOps as sdhci_mmio_le_ops ('le')
- Add an 'endianness' property to SDHCIState (default little endian)
- Set the 'io_ops' field in realize() after checking the property
- Add the sdhci_mmio_be_ops (big-endian) MemoryRegionOps.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20221101222934.52444-3-philmd@linaro.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>