fix(arm): only expose `arm_bl2_dyn_cfg_init` to BL2

The `arm_bl2_dyn_cfg_init` function is intended exclusively for BL2 - it
should not be compiled for any other bootloader image. This change hides
it for all but BL2.

Change-Id: I9fa95094dcc30f9fa4cc7bc5b3119ceae82df1ea
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/plat/arm/common/arm_dyn_cfg.c b/plat/arm/common/arm_dyn_cfg.c
index 99e2809..18ab5be 100644
--- a/plat/arm/common/arm_dyn_cfg.c
+++ b/plat/arm/common/arm_dyn_cfg.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2023, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2024, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -120,6 +120,7 @@
 }
 #endif /* CRYPTO_SUPPORT */
 
+#if IMAGE_BL2
 /*
  * BL2 utility function to initialize dynamic configuration specified by
  * FW_CONFIG. Populate the bl_mem_params_node_t of other FW_CONFIGs if
@@ -229,3 +230,4 @@
 		panic();
 	}
 }
+#endif /* IMAGE_BL2 */