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_ecdh.function b/tests/suites/test_suite_ecdh.function
index 1a33d81..640dc76 100644
--- a/tests/suites/test_suite_ecdh.function
+++ b/tests/suites/test_suite_ecdh.function
@@ -360,13 +360,13 @@
     mbedtls_ecdh_init( &srv );
     mbedtls_ecdh_init( &cli );
 
-    z_len = unhexify( z, z_str );
+    z_len = mbedtls_test_unhexify( z, z_str );
 
     rnd_info_A.buf = rnd_buf_A;
-    rnd_info_A.length = unhexify( rnd_buf_A, dA_str );
+    rnd_info_A.length = mbedtls_test_unhexify( rnd_buf_A, dA_str );
 
     rnd_info_B.buf = rnd_buf_B;
-    rnd_info_B.length = unhexify( rnd_buf_B, dB_str );
+    rnd_info_B.length = mbedtls_test_unhexify( rnd_buf_B, dB_str );
 
     /* The ECDH context is not guaranteed ot have an mbedtls_ecp_group structure
      * in every configuration, therefore we load it separately. */