[RFC 1/9] spi: spi-imx: cleanups and performance improvements

[Marc Kleine-Budde]

Hello,

this patch series first cleans up several sparse and checkpatch
warnings, then finished master -< controller conversion. Then PIO
based polling support is added. It's activated by default for
transfers smaller than 30 µs (like in the raspi SPI drivers). The last
patch optimized setup of the MX51_ECSPI_CONFIG register.

regards,
Marc