i2c: qcom-geni: Add support for GPI DMA

QUP Serial engines supports data transfers thru FIFO mode, SE DMA mode
and lastly GPI DMA mode. Former two are already supported and this adds
supports for the last mode.

In GPI DMA mode, the firmware is issued commands by driver to perform
DMA and setup the serial port.
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>