feat(stm32mp1-fdts): use /omit-if-no-ref/ for pins nodes

With the /omit-if-no-ref/ keyword in DT, the non-referenced nodes
are just removed. This allows reducing the size of device tree blobs.
Setting it before pins node allows a size reduction of more than 2kB.
The corresponding nodes can also be removed from BL2 and BL32 DT
overlays.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I6b4a4d227d5592e1d253a1b35da2dafaac2ddcae
diff --git a/fdts/stm32mp13-bl2.dtsi b/fdts/stm32mp13-bl2.dtsi
index 836e9ae..06db796 100644
--- a/fdts/stm32mp13-bl2.dtsi
+++ b/fdts/stm32mp13-bl2.dtsi
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
 /*
- * Copyright (C) STMicroelectronics 2022 - All Rights Reserved
+ * Copyright (c) 2022-2023, STMicroelectronics - All Rights Reserved
  */
 
 / {
@@ -32,13 +32,6 @@
 #if !STM32MP_USB_PROGRAMMER
 		/delete-node/ usbphyc@5a006000;
 #endif
-
-		pinctrl@50002000 {
-#if !STM32MP_EMMC && !STM32MP_SDMMC
-			/delete-node/ sdmmc1-b4-0;
-			/delete-node/ sdmmc2-b4-0;
-#endif
-		};
 	};
 
 	/*