reinstall aarch64-linux-gnu-gcc

After I used SDKmanager, my system have a aarch64 gcc tool named aarch64-linux-gnu-gcc, whose version is as bellow:

aarch64-linux-gnu-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

and it is old version. So I download new tool: gcc-linaro-7.3.1-2018.05-x86_64_aarch64-linux-gnu.tar.xz

but I don’t know replace the old version. The old version is installed in usr/aarch64-linux-gnu/bin.

Just need to “export CROSS_COMPILE=$path to the gcc bin file” when you build the kernel.

https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%2520Linux%2520Driver%2520Package%2520Development%2520Guide%2Fxavier_toolchain.html