Fix spurious * in regex

`grep mbedtls_des*` would pick up e.g. mbedtls_derive_xxx.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/components-configuration-crypto.sh b/tests/scripts/components-configuration-crypto.sh
index da0e180..93f7f77 100644
--- a/tests/scripts/components-configuration-crypto.sh
+++ b/tests/scripts/components-configuration-crypto.sh
@@ -2322,7 +2322,7 @@
     helper_libtestdriver1_make_main "$loc_accel_list"
 
     # Make sure this was not re-enabled by accident (additive config)
-    not grep mbedtls_des* library/des.o
+    not grep mbedtls_des library/des.o
 
     # Run the tests
     # -------------