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/host_test.function b/tests/suites/host_test.function
index 5688efd..e93b4e0 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -277,7 +277,7 @@
         {
             if ( verify_string( &val ) == 0 )
             {
-                *int_params_store = unhexify( (unsigned char *) val, val );
+                *int_params_store = mbedtls_test_unhexify( (unsigned char *) val, val );
                 *out++ = val;
                 *out++ = (char *)(int_params_store++);
             }