arm: dts: stm32mp15: alignment with v5.15-rc6

Device tree alignment with Linux kernel v5.15-rc6
- Set {bitclock,frame}-master phandles on ST DKx
- Add coprocessor detach mbox on stm32mp15x-dkx boards
- Add coprocessor detach mbox on stm32mp157c-ed1 board

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/arch/arm/dts/stm32mp157c-ed1.dts b/arch/arm/dts/stm32mp157c-ed1.dts
index 6e89f88..f62b46b 100644
--- a/arch/arm/dts/stm32mp157c-ed1.dts
+++ b/arch/arm/dts/stm32mp157c-ed1.dts
@@ -321,8 +321,8 @@
 &m4_rproc {
 	memory-region = <&retram>, <&mcuram>, <&mcuram2>, <&vdev0vring0>,
 			<&vdev0vring1>, <&vdev0buffer>;
-	mboxes = <&ipcc 0>, <&ipcc 1>, <&ipcc 2>;
-	mbox-names = "vq0", "vq1", "shutdown";
+	mboxes = <&ipcc 0>, <&ipcc 1>, <&ipcc 2>, <&ipcc 3>;
+	mbox-names = "vq0", "vq1", "shutdown", "detach";
 	interrupt-parent = <&exti>;
 	interrupts = <68 1>;
 	status = "okay";