refactor(mbedtls): remove mbedtls 2.x support

Deprecation notice was sent to the community and no objection was
raised, so removing mbedtls 2.x support.

Change-Id: Id3eb98b55692df98aabe6a7c5a5ec910222c8abd
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
diff --git a/plat/st/common/common.mk b/plat/st/common/common.mk
index f49112d..b9b62c0 100644
--- a/plat/st/common/common.mk
+++ b/plat/st/common/common.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2023, STMicroelectronics - All Rights Reserved
+# Copyright (c) 2023-2024, STMicroelectronics - All Rights Reserved
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -183,12 +183,10 @@
 MBEDTLS_MAJOR=$(shell grep -hP "define MBEDTLS_VERSION_MAJOR" \
 ${MBEDTLS_DIR}/include/mbedtls/*.h | grep -oe '\([0-9.]*\)')
 
-ifeq (${MBEDTLS_MAJOR}, 2)
-MBEDTLS_CONFIG_FILE		?=	"<stm32mp_mbedtls_config-2.h>"
-endif
-
 ifeq (${MBEDTLS_MAJOR}, 3)
 MBEDTLS_CONFIG_FILE		?=	"<stm32mp_mbedtls_config-3.h>"
+else
+$(error Error: TF-A only supports MbedTLS versions > 3.x)
 endif
 endif