tests: Add mbedtls_test_ prefix to *hexify functions

Add mbedtls_test_ prefix to hexify() and unhexify()
test helper functions.

Command to change *.function files:
find . -name "*.function" -exec awk -i inplace \
    '{sub(/(un|)hexify\>/,"mbedtls_test_&")}1' {} \;

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/suites/test_suite_hkdf.function b/tests/suites/test_suite_hkdf.function
index 3e87207..c08d8f3 100644
--- a/tests/suites/test_suite_hkdf.function
+++ b/tests/suites/test_suite_hkdf.function
@@ -28,17 +28,17 @@
     const mbedtls_md_info_t *md = mbedtls_md_info_from_type( md_alg );
     TEST_ASSERT( md != NULL );
 
-    ikm_len = unhexify( ikm, hex_ikm_string );
-    salt_len = unhexify( salt, hex_salt_string );
-    info_len = unhexify( info, hex_info_string );
-    okm_len = unhexify( expected_okm, hex_okm_string );
+    ikm_len = mbedtls_test_unhexify( ikm, hex_ikm_string );
+    salt_len = mbedtls_test_unhexify( salt, hex_salt_string );
+    info_len = mbedtls_test_unhexify( info, hex_info_string );
+    okm_len = mbedtls_test_unhexify( expected_okm, hex_okm_string );
 
     ret = mbedtls_hkdf( md, salt, salt_len, ikm, ikm_len, info, info_len, okm,
                         okm_len);
     TEST_ASSERT( ret == 0 );
 
-    // Run hexify on it so that it looks nicer if the assertion fails
-    hexify( okm_hex, okm, okm_len );
+    // Run mbedtls_test_hexify on it so that it looks nicer if the assertion fails
+    mbedtls_test_hexify( okm_hex, okm, okm_len );
     TEST_ASSERT( !strcmp( (char *)okm_hex, hex_okm_string ) );
 }
 /* END_CASE */