Removes unused variables in test_suite_rsa.function

CI was failing on check_params due to
MBEDTLS_RSA_PRIVATE being assigned to a now
superfluous variable. The variable has been
as well as another superfluous variable.
This should correct the CI issue.

Signed-off-by: Thomas Daubney <thomas.daubney@arm.com>
diff --git a/tests/suites/test_suite_rsa.function b/tests/suites/test_suite_rsa.function
index 442e857..efea5c1 100644
--- a/tests/suites/test_suite_rsa.function
+++ b/tests/suites/test_suite_rsa.function
@@ -23,8 +23,6 @@
     mbedtls_rsa_context ctx;
     const int valid_padding = MBEDTLS_RSA_PKCS_V21;
     const int invalid_padding = 42;
-    const int valid_mode = MBEDTLS_RSA_PRIVATE;
-    const int invalid_mode = 42;
     unsigned char buf[42] = { 0 };
     size_t olen;