Makefile: Add 'make run' command for platform specific run

Makes for easy and quick build-run one-stop command.

For now only added for qemu targets. It can be added for
any platform having simulator/emulator (such as QEMU).

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Anup Patel <anup.patel@wdc.com>