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/all.sh b/tests/scripts/all.sh
index 3200883..229e6df 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -2140,7 +2140,7 @@
     loc_accel_flags="$loc_accel_flags $( echo "$loc_accel_list" | sed 's/[^ ]* */-DMBEDTLS_PSA_ACCEL_&/g' )"
     make CFLAGS="$ASAN_CFLAGS -Werror -I../tests/include -I../tests -DPSA_CRYPTO_DRIVER_TEST -DMBEDTLS_TEST_LIBTESTDRIVER1 $loc_accel_flags" LDFLAGS="-ltestdriver1 $ASAN_CFLAGS"
 
-    not grep mbedtls_des* library/des.o
+    not grep mbedtls_des library/des.o
 
     msg "test: MBEDTLS_PSA_CRYPTO_CONFIG with accelerated hash"
     make test