arm64: dts: fix i2c pinconf sleep state function

This patch fixes the i2c pinctrl sleep state by changing the pinconf
function to be in gpio mode rather than i2c.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Andy Gross <agross@codeaurora.org>