armcm_reset: Add a new helper file defining command_reset()

Add a generic ARM Cortex-M implementation of the "reset" command.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/armcm_reset.c

@@ -0,0 +1,15 @@
+// Generic reset command handler for ARM Cortex-M boards
+//
+// Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "board/internal.h" // NVIC_SystemReset
+#include "command.h" // DECL_COMMAND_FLAGS
+
+void
+command_reset(uint32_t *args)
+{
+    NVIC_SystemReset();
+}
+DECL_COMMAND_FLAGS(command_reset, HF_IN_SHUTDOWN, "reset");