i2c: qcom: geni: use geni device ptr for dma mapping

Even during GSI mode, geni dma is used for data transfer
between DDR and serial engine. Use geni device ptr for
correct iova mapping.

CRs-Fixed: 2102639
Change-Id: Iad263905e9271faa435f6c7f87bfdd2fe1f4bcd4
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>