i2c: qcom-geni: Use the correct return value

The introduction of GPI support moved things around and instead of
returning the result from geni_i2c_xfer() the number of messages in the
request was returned, ignoring the actual result. Fix this.

Fixes: d8703554 ("i2c: qcom-geni: Add support for GPI DMA")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>