package/libiec61850: add mbedtls optional dependency

mbedtls is an optional dependency since bump to version 1.5.0 in
commit a42e0e4600be785fa750c6b481c41a76d041df03 and
https://github.com/mz-automation/libiec61850/commit/19f2cbf0e7066753476ff8c38c07a6f0df73a622

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 4d07864d4c1b7d964e23f8ab75f5c6f828a674c5)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libiec61850/libiec61850.mk

@@ -15,4 +15,11 @@ LIBIEC61850_CONF_OPTS = -DBUILD_PYTHON_BINDINGS=OFF
 # https://github.com/mz-automation/libiec61850/issues/442
 LIBIEC61850_IGNORE_CVES += CVE-2023-27772
 
+ifeq ($(BR2_PACKAGE_MBEDTLS),y)
+LIBIEC61850_DEPENDENCIES += mbedtls
+LIBIEC61850_CONF_OPTS += -DCONFIG_USE_EXTERNAL_MBEDTLS_DYNLIB=ON
+else
+LIBIEC61850_CONF_OPTS += -DCONFIG_USE_EXTERNAL_MBEDTLS_DYNLIB=OFF
+endif
+
 $(eval $(cmake-package))