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_ecdsa.function b/tests/suites/test_suite_ecdsa.function
index 2844bea..688ad06 100644
--- a/tests/suites/test_suite_ecdsa.function
+++ b/tests/suites/test_suite_ecdsa.function
@@ -447,9 +447,9 @@
     mbedtls_ecdsa_init( &ctx );
     mbedtls_ecdsa_restart_init( &rs_ctx );
 
-    hash_len = unhexify(hash, h_str);
-    sig_len = unhexify(sig, s_str);
-    pk_len = unhexify(pk, k_str);
+    hash_len = mbedtls_test_unhexify(hash, h_str);
+    sig_len = mbedtls_test_unhexify(sig, s_str);
+    pk_len = mbedtls_test_unhexify(pk, k_str);
 
     TEST_ASSERT( mbedtls_ecp_group_load( &ctx.grp, id ) == 0 );
     TEST_ASSERT( mbedtls_ecp_point_read_binary( &ctx.grp, &ctx.Q, pk, pk_len ) == 0 );
@@ -521,7 +521,7 @@
 
     TEST_ASSERT( mbedtls_ecp_group_load( &ctx.grp, id ) == 0 );
     TEST_ASSERT( mbedtls_mpi_read_string( &ctx.d, 16, d_str ) == 0 );
-    slen_check = unhexify( sig_check, sig_str );
+    slen_check = mbedtls_test_unhexify( sig_check, sig_str );
 
     md_info = mbedtls_md_info_from_type( md_alg );
     TEST_ASSERT( md_info != NULL );