Improve mbedtls_mpi_core_lt_ct() unit tests

- Improve test descriptions
- Add more test cases with return value of 1
- Remove the mbedtls prefix from the test function

Signed-off-by: Janos Follath <janos.follath@arm.com>
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index b75f0f8..23e270b 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -722,7 +722,7 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void mbedtls_mpi_core_lt_ct( data_t * input_X, data_t * input_Y, int input_ret )
+void mpi_core_lt_ct( data_t * input_X, data_t * input_Y, int input_ret )
 {
     #define MAX_LEN 64
     mbedtls_mpi_uint X[MAX_LEN];