toolchain: make the arm-linux-* can by execute

change the mode to 755. The old mode is 644

Signed-off-by: Jack Tan <jiankemeng@gmail.com>
kernel: add the tool netcat into ramfs

Signed-off-by: Jack Tan <jiankemeng@gmail.com>
kernel: add a network up script into the ramfs

You can use the netcat to transfer files into
ramfs.

Signed-off-by: Jack Tan <jiankemeng@gmail.com>