Revert "GCC: Upgrade to version 9.2-2019.12 of toolchain"

This reverts commit de9bf1d8a2de952bfc17cdf7082b41f9c185e54d.

Change-Id: Iebb6297ce290a10ee850bf6a9c71e7eb530b085f
diff --git a/docs/plat/imx8m.rst b/docs/plat/imx8m.rst
index 0116b34..8acd13c 100644
--- a/docs/plat/imx8m.rst
+++ b/docs/plat/imx8m.rst
@@ -28,7 +28,7 @@
 
    .. code:: shell
 
-       CROSS_COMPILE=aarch64-none-elf- make PLAT=<Target_SoC> bl31
+       CROSS_COMPILE=aarch64-linux-gnu- make PLAT=<Target_SoC> bl31
 
    Target_SoC should be "imx8mq" for i.MX8MQ SoC.
    Target_SoC should be "imx8mm" for i.MX8MM SoC.