mtd/spi: add MTD support to spi flash
mtd-spi: allow winbond erasesize to be specified

The default erasesize is 4KB which makes for very slow flash operations
on large parts.  This allows overriding the size in board config.
imx: fixed ventana SPI flash_boot script

- removed improperly placed null termination that was truncating script
- include kernel in mtdparts
imx: ventana: fixed usb-otg ID GPIO config
imx: ventana: add board prop to devicetree

The 'model' prop shows the devicetree machine whereas the 'board' property
will show the exact Gateworks model number.
imx: ventana: disable pps node if no gps
imx: ventana: remove dead code
imx: ventana: fix analog video decoder enable GPIO