TFTF: Add support for FVP platforms with SMT capabilities

This patch adds support for Simultaneously MultiThreaded (SMT)
cores on FVP models. Number of threads per CPU is passed in
FVP_MAX_PE_PER_CPU build parameter which can be set either to
1 or 2. This option defaults to 1.

Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Change-Id: Ib0e2afe429e8f24b8a74ad6ee98750ed1ac121fb
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 41d0ba7..5dc7074 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -425,6 +425,12 @@
    platform makefile is free to override this value if Firmware Update is
    supported on this platform.
 
+Arm FVP platform specific build options
+'''''''''''''''''''''''''''''''''''''''
+
+-  ``FVP_MAX_PE_PER_CPU``: Sets the maximum number of PEs implemented on any CPU
+   in the system. It can take either 1 or 2 values. This option defaults to 1.
+
 Checking source code style
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