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

This reverts commit de9bf1d8a2de952bfc17cdf7082b41f9c185e54d.

Change-Id: Iebb6297ce290a10ee850bf6a9c71e7eb530b085f
diff --git a/docs/plat/intel-stratix10.rst b/docs/plat/intel-stratix10.rst
index 5f33d12..7f8d18e 100644
--- a/docs/plat/intel-stratix10.rst
+++ b/docs/plat/intel-stratix10.rst
@@ -41,7 +41,7 @@
 
 .. code:: bash
 
-       make CROSS_COMPILE=aarch64-none-elf- bl2 fip PLAT=stratix10
+       make CROSS_COMPILE=aarch64-linux-gnu- bl2 fip PLAT=stratix10
        BL33=PEI.ROM
 
 Install Procedure