Remove support for the SMC Calling Convention 2.0

This reverts commit 2f370465241c ("Add support for the SMC Calling
Convention 2.0").

SMCCC v2.0 is no longer required for SPM, and won't be needed in the
future. Removing it makes the SMC handling code less complicated.

The SPM implementation based on SPCI and SPRT was using it, but it has
been adapted to SMCCC v1.0.

Change-Id: I36795b91857b2b9c00437cfbfed04b3c1627f578
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index b50de37..a479fb0 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -628,11 +628,6 @@
    pages" section in `Firmware Design`_. This flag is disabled by default and
    affects all BL images.
 
--  ``SMCCC_MAJOR_VERSION``: Numeric value that indicates the major version of
-   the SMC Calling Convention that the Trusted Firmware supports. The only two
-   allowed values are 1 and 2, and it defaults to 1. The minor version is
-   determined using this value.
-
 -  ``SPD``: Choose a Secure Payload Dispatcher component to be built into TF-A.
    This build option is only valid if ``ARCH=aarch64``. The value should be
    the path to the directory containing the SPD source, relative to
@@ -2045,7 +2040,7 @@
 
 --------------
 
-*Copyright (c) 2013-2018, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2013-2019, Arm Limited and Contributors. All rights reserved.*
 
 .. _Linaro: `Linaro Release Notes`_
 .. _Linaro Release: `Linaro Release Notes`_