Escape hexpairs characters RFC 4514

Converts none ascii to escaped hexpairs in mbedtls_x509_dn_gets and
interprets hexpairs in mbedtls_x509_string_to_names.

Signed-off-by: Agathiyan Bragadeesh <agathiyan.bragadeesh2@arm.com>
diff --git a/tests/suites/test_suite_x509write.data b/tests/suites/test_suite_x509write.data
index e50f590..0987fae 100644
--- a/tests/suites/test_suite_x509write.data
+++ b/tests/suites/test_suite_x509write.data
@@ -196,5 +196,14 @@
 X509 String to Names #10 (Escape ' ' at beginning and end of string)
 mbedtls_x509_string_to_names:"C=NL, O= Off spark , OU=PolarSSL":"C=NL, O=\\ Off spark\\ , OU=PolarSSL":0
 
+X509 String to Names #11 (Escape ascii hexpairs)
+mbedtls_x509_string_to_names:"C=NL, O=Of\\66spark, OU=PolarSSL":"C=NL, O=Offspark, OU=PolarSSL":0
+
+X509 String to Names #12 (Escape non-ascii hexpairs)
+mbedtls_x509_string_to_names:"C=NL, O=Of\\00spark, OU=PolarSSL":"C=NL, O=Of\\00spark, OU=PolarSSL":0
+
+X509 String to Names #13 (Invalid hexpairs)
+mbedtls_x509_string_to_names:"C=NL, O=Of\\flspark, OU=PolarSSL":"":MBEDTLS_ERR_X509_INVALID_NAME
+
 Check max serial length
 x509_set_serial_check: