ARM: dts: stm32: Add STM32MP1 I2C6 SDA/SCL pinmux

Add SDA/SCL pinmux lines for I2C6 on STM32MP1.

This support adds both in default and sleep states.
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm/boot/dts/stm32mp15-pinctrl.dtsi

@@ -2041,6 +2041,23 @@ pins {
 		};
 	};
 
+	i2c6_pins_a: i2c6-0 {
+		pins {
+			pinmux = <STM32_PINMUX('Z', 6, AF2)>, /* I2C6_SCL */
+				 <STM32_PINMUX('Z', 7, AF2)>; /* I2C6_SDA */
+			bias-disable;
+			drive-open-drain;
+			slew-rate = <0>;
+		};
+	};
+
+	i2c6_sleep_pins_a: i2c6-sleep-0 {
+		pins {
+			pinmux = <STM32_PINMUX('Z', 6, ANALOG)>, /* I2C6_SCL */
+				 <STM32_PINMUX('Z', 7, ANALOG)>; /* I2C6_SDA */
+		};
+	};
+
 	spi1_pins_a: spi1-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('Z', 0, AF5)>, /* SPI1_SCK */