[sw/device] Remove redundant #include <stdlib.h>

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
diff --git a/sw/device/tests/hmac/sha256_test.c b/sw/device/tests/hmac/sha256_test.c
index 433b1e5..de812ba 100644
--- a/sw/device/tests/hmac/sha256_test.c
+++ b/sw/device/tests/hmac/sha256_test.c
@@ -2,8 +2,6 @@
 // Licensed under the Apache License, Version 2.0, see LICENSE for details.
 // SPDX-License-Identifier: Apache-2.0
 
-#include <stdlib.h>
-
 #include "sw/device/lib/common.h"
 #include "sw/device/lib/flash_ctrl.h"
 #include "sw/device/lib/hw_sha256.h"
diff --git a/sw/device/tests/rv_timer/rv_timer_test.c b/sw/device/tests/rv_timer/rv_timer_test.c
index d0026a1..88035be 100644
--- a/sw/device/tests/rv_timer/rv_timer_test.c
+++ b/sw/device/tests/rv_timer/rv_timer_test.c
@@ -2,8 +2,6 @@
 // Licensed under the Apache License, Version 2.0, see LICENSE for details.
 // SPDX-License-Identifier: Apache-2.0
 
-#include <stdlib.h>
-
 #include "sw/device/lib/common.h"
 #include "sw/device/lib/irq.h"
 #include "sw/device/lib/rv_timer.h"