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>
mxs: Fix MMC reset to avoid write errors and timeout  in iMX23

This does the same reset mask as done in v3.7 Linux kernel code; it
fixed the saveenv command in mx23evk.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mx23: Use PIO mode support for MMC

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
mxs: Boost the memory power supply

The memory power supply on MX23 didn't pump out enough juice into
the DRAM chip, thus caused occasional memory corruption. Fix this.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>