arm64: dts: sc7180: Add a comment to i2c7 about external pullup

Make i2c7 symmetric with the other i2c busses and comment that we have
no internal pull because there is an external one.
Reviewed-by: NRajendra Nayak <rnayak@codeaurora.org>
Fixes: ba3fc649 ("arm64: dts: sc7180: Add qupv3_0 and qupv3_1")
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20191210163530.2.I8d4cbb3d7ac5824f8e950c53038df8c27a512905@changeidSigned-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/sc7180-idp.dts

@@ -311,6 +311,8 @@
 	pinconf {
 		pins = "gpio6", "gpio7";
 		drive-strength = <2>;
+
+		/* Has external pullup */
 		bias-disable;
 	};
 };