ARM: dts: stm32: remove useless interrupt-names property on stm32f746

Driver doesn't use interrupt's name to get it so remove it from
the node.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f746.dtsi

@@ -304,7 +304,6 @@ rtc: rtc@40002800 {
 			assigned-clock-parents = <&rcc 1 CLK_LSE>;
 			interrupt-parent = <&exti>;
 			interrupts = <17 1>;
-			interrupt-names = "alarm";
 			st,syscfg = <&pwrcfg 0x00 0x100>;
 			status = "disabled";
 		};