dt-bindings: clock: stm32mp1: support disabled fixed clock

Add precision for disabled fixed clock in stm32mp1 binding.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/doc/device-tree-bindings/clock/st,stm32mp1.txt b/doc/device-tree-bindings/clock/st,stm32mp1.txt
index 02e1460..ec1d703 100644
--- a/doc/device-tree-bindings/clock/st,stm32mp1.txt
+++ b/doc/device-tree-bindings/clock/st,stm32mp1.txt
@@ -164,8 +164,10 @@
   - clk-csi
 
 At boot the clock tree initialization will
-  - enable oscillators present in device tree
+  - enable oscillators present in device tree and not disabled
+    (node with status="disabled"),
   - disable HSI oscillator if the node is absent (always activated by bootrom)
+    and not disabled (node with status="disabled").
 
 Optional properties :