dts: Add SDHC configuration for STM32.

This commit adds the main DTS configurations required
to enable SDHC support on STM32.

Signed-off-by: Sara Touqan <[email protected]>

Author: ExaltZephyr

dts/bindings/sdhc/st,stm32-sdhc.yaml

@@ -0,0 +1,15 @@
+compatible: "st,stm32-sdhc"
+
+bus: sd
+
+include: "st,stm32-sdmmc.yaml"
+
+properties:
+  hw-flow-control:
+    type: boolean
+    description: Set to enable RTS/CTS flow control at boot time
+
+  sdhi-on-gpios:
+    description: |
+      GPIO used to enable/disable the SDHI.
+    type: phandle-array