ARM: dts: stm32: keep uart nodes behavior on stm32mp157a-stinger96

DMA configuration is added to uart nodes in stm32mp15x device tree.
Delete uart4 DMA property in stm32mp157a-stinger96 board device tree to
keep console in irq mode, as DMA support for console has been removed
from the driver by commit e359b4411c28 ("serial: stm32: fix threaded
interrupt handling").
Delete also usart2 and uart7 DMA property to keep current behavior.

Signed-off-by: Erwan Le Ray <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

arch/arm/boot/dts/stm32mp157a-stinger96.dtsi

···
 	pinctrl-0 = <&usart2_pins_b>;
 	pinctrl-1 = <&usart2_sleep_pins_b>;
 	st,hw-flow-ctrl;
+	/delete-property/dmas;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
···
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart4_pins_c>;
 	st,hw-flow-ctrl;
+	/delete-property/dmas;
+	/delete-property/dma-names;
 	status = "okay";
 };
 
···
 &uart7 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart7_pins_b>;
+	/delete-property/dmas;
+	/delete-property/dma-names;
 	status = "okay";
 };