ARM: dts: stm32: Update qspi bindings for stm32f746

Align qspi bindings following kernel dt-bindings
Documentation/devicetree/bindings/mtd/stm32-quadspi.txt
from kernel v4.17-rc1.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>

arch/arm/dts/stm32f746.dtsi

@@ -88,7 +88,7 @@
 			#address-cells = <1>;
 			#size-cells = <0>;
 			reg = <0xA0001000 0x1000>, <0x90000000 0x10000000>;
-			reg-names = "QuadSPI", "QuadSPI-memory";
+			reg-names = "qspi", "qspi_mm";
 			interrupts = <92>;
 			spi-max-frequency = <108000000>;
 			clocks = <&rcc 0 STM32F7_AHB3_CLOCK(QSPI)>;