mx23: Add SSP registers map

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23: Use XFER_COUNT field in HW_SSP_CTRL0 register in MMC PIO mode

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23: Fix transfer size setting for SPI

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23evk: Add initial board support

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23_olinuxino: Add MMC support

Signed-off-by: Marek Vasut <marex@denx.de>
mx23_olinuxino: Skip MMC Card detection

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23_olinuxino: Add default environment

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>