Fix copypasta in test case description

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index 36e6672..59fd782 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -34,7 +34,7 @@
 Base test mpi_read_write_string #3 (Negative decimal, leading 0)
 mpi_read_write_string:10:"-023":10:"-23":100:0:0
 
-Base test mpi_read_write_string #3 (Negative decimal -> hex)
+Base test mpi_read_write_string #3 (Negative hex -> decimal)
 mpi_read_write_string:16:"-20":10:"-32":100:0:0
 
 Base test mpi_read_write_string #3 (Negative hex)