Update to the new name in usages as well

Somehow the uses of the function were missed when renaming.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/tests/suites/test_suite_cipher.function b/tests/suites/test_suite_cipher.function
index 2444ef9..3eb4625 100644
--- a/tests/suites/test_suite_cipher.function
+++ b/tests/suites/test_suite_cipher.function
@@ -1272,8 +1272,8 @@
     size_t calculated_len;
 
     TEST_CF_SECRET(decrypted_block->x, decrypted_block->len);
-    ret = get_pkcs_padding(decrypted_block->x, decrypted_block->len,
-                           &calculated_len);
+    ret = mbedtls_get_pkcs_padding(decrypted_block->x, decrypted_block->len,
+                                   &calculated_len);
     TEST_CF_PUBLIC(decrypted_block->x, decrypted_block->len);
 
     TEST_EQUAL(ret, exp_ret);