asn1: use the new symbol to guard dependencies of ECDSA conversion functions

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/library/asn1parse.c b/library/asn1parse.c
index c02b233..e33fdf7 100644
--- a/library/asn1parse.c
+++ b/library/asn1parse.c
@@ -7,7 +7,8 @@
 
 #include "common.h"
 
-#if defined(MBEDTLS_ASN1_PARSE_C) || defined(MBEDTLS_X509_CREATE_C)
+#if defined(MBEDTLS_ASN1_PARSE_C) || defined(MBEDTLS_X509_CREATE_C) || \
+    defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA)
 
 #include "mbedtls/asn1.h"
 #include "mbedtls/platform_util.h"
@@ -73,7 +74,7 @@
 
     return mbedtls_asn1_get_len(p, end, len);
 }
-#endif /* MBEDTLS_ASN1_PARSE_C || MBEDTLS_X509_CREATE_C */
+#endif /* MBEDTLS_ASN1_PARSE_C || MBEDTLS_X509_CREATE_C || MBEDTLS_PSA_UTIL_HAVE_ECDSA */
 
 #if defined(MBEDTLS_ASN1_PARSE_C)
 int mbedtls_asn1_get_bool(unsigned char **p,