tests: Add mbedtls_test_ prefix to hexcmp()

Add mbedtls_test_ prefix to hexcmp() test helper
function.

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

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/suites/test_suite_gcm.function b/tests/suites/test_suite_gcm.function
index 1fcb681..ea2c91d 100644
--- a/tests/suites/test_suite_gcm.function
+++ b/tests/suites/test_suite_gcm.function
@@ -55,8 +55,8 @@
     {
         TEST_ASSERT( mbedtls_gcm_crypt_and_tag( &ctx, MBEDTLS_GCM_ENCRYPT, src_str->len, iv_str->x, iv_str->len, add_str->x, add_str->len, src_str->x, output, tag_len, tag_output ) == 0 );
 
-        TEST_ASSERT( hexcmp( output, hex_dst_string->x, src_str->len, hex_dst_string->len ) == 0 );
-        TEST_ASSERT( hexcmp( tag_output, hex_tag_string->x, tag_len, hex_tag_string->len ) == 0 );
+        TEST_ASSERT( mbedtls_test_hexcmp( output, hex_dst_string->x, src_str->len, hex_dst_string->len ) == 0 );
+        TEST_ASSERT( mbedtls_test_hexcmp( tag_output, hex_tag_string->x, tag_len, hex_tag_string->len ) == 0 );
     }
 
 exit:
@@ -94,7 +94,7 @@
         {
             TEST_ASSERT( ret == 0 );
 
-            TEST_ASSERT( hexcmp( output, pt_result->x, src_str->len, pt_result->len ) == 0 );
+            TEST_ASSERT( mbedtls_test_hexcmp( output, pt_result->x, src_str->len, pt_result->len ) == 0 );
         }
     }