[PATCH v3 0/4]Add Freescale DSPI driver for Vybrid VF610 platform

[Chao Fu]

This driver is the SPI master mode driver and has been tested on Vybrid VF610TWR board.
Changes in v2:
- Add a document for DSPI driver under Documentation/devicetree/bindings/spi/.
- Move spi-num-chipselects info dtsi nodes.
Changes in v3:
- Remove two dts properties(dbr,pbr) from  documentation bindings, they will be calculated in code.
- Update driver code in bitbang framework.
- Brief some functions in driver code.