ARM: dts: stm32: Fix sdio2 rcc hard coded value

Replace sdio2 rcc hard coded clock value by its macro.
Signed-off-by: NPatrice Chotard <patrice.chotard@st.com>
Signed-off-by: NAlexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32f746.dtsi

@@ -432,7 +432,7 @@
 			compatible = "arm,pl180", "arm,primecell";
 			arm,primecell-periphid = <0x00880180>;
 			reg = <0x40011c00 0x400>;
-			clocks = <&rcc 0 167>;
+			clocks = <&rcc 0 STM32F7_APB2_CLOCK(SDMMC2)>;
 			clock-names = "apb_pclk";
 			interrupts = <103>;
 			max-frequency = <48000000>;