ARM: dts: stm32: add gadget fifo sizes to usbotg_hs on stm32f746

USB OTG HS on STM32F746 can also be used as Peripheral (gadget), so
this patch adds DWC2 gadget mode fifo sizes bindings.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f746.dtsi

@@ -576,6 +576,9 @@ usbotg_hs: usb@40040000 {
 			interrupts = <77>;
 			clocks = <&rcc 0 STM32F7_AHB1_CLOCK(OTGHS)>;
 			clock-names = "otg";
+			g-rx-fifo-size = <256>;
+			g-np-tx-fifo-size = <32>;
+			g-tx-fifo-size = <128 128 64 64 64 64 32 32>;
 			status = "disabled";
 		};