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

This reverts commit de9bf1d8a2de952bfc17cdf7082b41f9c185e54d.

Change-Id: Iebb6297ce290a10ee850bf6a9c71e7eb530b085f
diff --git a/docs/plat/arm/fvp/index.rst b/docs/plat/arm/fvp/index.rst
index 37010e1..b6396b9 100644
--- a/docs/plat/arm/fvp/index.rst
+++ b/docs/plat/arm/fvp/index.rst
@@ -223,7 +223,7 @@
 
 .. code:: shell
 
-    CROSS_COMPILE=aarch64-none-elf-  \
+    CROSS_COMPILE=aarch64-linux-gnu-  \
     make PLAT=fvp DEBUG=1             \
     RESET_TO_BL31=1                   \
     ARM_LINUX_KERNEL_AS_BL33=1        \