arm64: dts: qcom: msm8916: Pull-up the UART RX pin

With UART disconnected, no one is driving the UART RX line. It will be
floating, which can end up producing garbage on stdin.

Reliable UART is particularly important in early boot stages, otherwise
an autoboot sequence might be interrupted, so bootph-all is also added
to the RX pin.

Co-developed-by: Sam Day <me@samcday.com>
Signed-off-by: Sam Day <me@samcday.com>
Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>

arch/arm64/boot/dts/qcom/msm8916.dtsi

@@ -1279,10 +1279,20 @@
 			};
 
 			blsp_uart2_default: blsp-uart2-default-state {
-				pins = "gpio4", "gpio5";
-				function = "blsp_uart2";
-				drive-strength = <16>;
-				bias-disable;
+				tx-pins {
+					pins = "gpio4";
+					function = "blsp_uart2";
+					drive-strength = <16>;
+					bias-disable;
+				};
+				rx-pins {
+					pins = "gpio5";
+					function = "blsp_uart2";
+					drive-strength = <16>;
+					bias-pull-up;
+					bootph-all;
+				};
+
 			};
 
 			blsp_uart2_sleep: blsp-uart2-sleep-state {