ARM: DT: stm32f7: add gpio device tree nodes

Also created alias for gpios for stm32f7 discovery board. Based on these
aliases, it would be possible to get gpio devices by sequence.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
cc: Christophe KERELLO <christophe.kerello@st.com>
diff --git a/arch/arm/dts/stm32f746-disco.dts b/arch/arm/dts/stm32f746-disco.dts
index f098d2e..f830aa9 100644
--- a/arch/arm/dts/stm32f746-disco.dts
+++ b/arch/arm/dts/stm32f746-disco.dts
@@ -65,6 +65,18 @@
 	aliases {
 		serial0 = &usart1;
 		spi0 = &qspi;
+		/* Aliases for gpios so as to use sequence */
+		gpio0 = &gpioa;
+		gpio1 = &gpiob;
+		gpio2 = &gpioc;
+		gpio3 = &gpiod;
+		gpio4 = &gpioe;
+		gpio5 = &gpiof;
+		gpio6 = &gpiog;
+		gpio7 = &gpioh;
+		gpio8 = &gpioi;
+		gpio9 = &gpioj;
+		gpio10 = &gpiok;
 	};
 };