spi: dw-mid: convert to use dw_dmac instead of intel_mid_dma

intel_mid_dma seems to be unmaintained for a long time. Moreover, the IP block
of DMA itself is the same in both dw_dmac and intel_mid_dma. This patch moves
spi-dw-midpci to use dw_dmac driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>