ARM: dts: stm32: Add SAI2A pins B pinmux entry on stm32mp1

Add pinmux entry for SAI2A with alternative pin configuration.
This is useful in combination with sai2b_pins_b e.g. for codecs
like SGTL5000.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: linux-stm32@st-md-mailman.stormreply.com
To: linux-arm-kernel@lists.infradead.org
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

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

@@ -719,6 +719,26 @@ pins {
 		};
 	};
 
+
+	sai2a_pins_b: sai2a-2 {
+		pins1 {
+			pinmux = <STM32_PINMUX('I', 6, AF10)>,	/* SAI2_SD_A */
+				 <STM32_PINMUX('I', 7, AF10)>,	/* SAI2_FS_A */
+				 <STM32_PINMUX('D', 13, AF10)>;	/* SAI2_SCK_A */
+			slew-rate = <0>;
+			drive-push-pull;
+			bias-disable;
+		};
+	};
+
+	sai2a_sleep_pins_b: sai2a-sleep-3 {
+		pins {
+			pinmux = <STM32_PINMUX('I', 6, ANALOG)>,  /* SAI2_SD_A */
+				 <STM32_PINMUX('I', 7, ANALOG)>,  /* SAI2_FS_A */
+				 <STM32_PINMUX('D', 13, ANALOG)>; /* SAI2_SCK_A */
+		};
+	};
+
 	sai2b_pins_a: sai2b-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('E', 12, AF10)>, /* SAI2_SCK_B */