boards: opta: revert change of qspi flash spi-bus-width

This fixes writes to the flash, and causes the following sample
code to work again: samples/drivers/spi_flash

Signed-off-by: Mark O'Donovan <[email protected]>

Author: shiftee

boards/arduino/opta/arduino_opta_stm32h747xx_m7.dts

@@ -163,8 +163,7 @@ zephyr_udc0: &usbotg_fs {
 		size = <DT_SIZE_M(128)>; /* 128 MBits */
 		qspi-max-frequency = <80000000>;
 		jedec-id = [01 1f 89];
-		spi-bus-width = <4>;
-		quad-enable-requirements = "NONE";
+		spi-bus-width = <2>;
 		status = "okay";
 
 		/* The following partitions are valid only if the Opta external flash