spi: dw-mid: take care of FIFO overrun/underrun when do DMA

In according to documentation SPI in DMA mode may encounter underrun/overrun
failures in rare cases. When such failure occurs, an error recovery protocol is
expected to be implemented in the device driver so that the failed transaction
can be restarted.

This patch enables FIFO overrun / underrun interrupts in DMA case and adds a
handler for that.

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