i2c: qcom-geni: Fix GPI DMA buffer sync-back

Fix i2c transfers using GPI DMA mode for all message types that do not set
the I2C_M_DMA_SAFE flag (e.g. SMBus "read byte").

In this case a bounce buffer is returned by i2c_get_dma_safe_msg_buf(),
and it has to synced back to the message after the transfer is done.

Add missing assignment of dma buffer in geni_i2c_gpi().

Set xferred in i2c_put_dma_safe_msg_buf() to true in case of no error to
ensure the sync-back of this dma buffer to the message.

Fixes: d8703554 ("i2c: qcom-geni: Add support for GPI DMA")
Signed-off-by: Robin Reckmann <robin.reckmann@gmail.com>
Tested-by: Luca Weiss <luca.weiss@fairphone.com>
Tested-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Konrad Dybcio <konrad.dybcio@somainline.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>