SPCI is now called PSA FF-A

SPCI is renamed as PSA FF-A which stands for Platform Security
Architecture Firmware Framework for A class processors.
This patch replaces the occurrence of SPCI with PSA FF-A(in documents)
or simply FFA(in code).

Change-Id: I4ab10adb9ffeef1ff784641dfafd99f515133760
Signed-off-by: J-Alves <joao.alves@arm.com>
diff --git a/docs/global_substitutions.txt b/docs/global_substitutions.txt
index 4dda1dc..d33155b 100644
--- a/docs/global_substitutions.txt
+++ b/docs/global_substitutions.txt
@@ -14,6 +14,7 @@
 .. |EHF| replace:: :term:`EHF`
 .. |FCONF| replace:: :term:`FCONF`
 .. |FDT| replace:: :term:`FDT`
+.. |FFA| replace:: :term:`FFA`
 .. |FIP| replace:: :term:`FIP`
 .. |FVP| replace:: :term:`FVP`
 .. |FWU| replace:: :term:`FWU`
@@ -44,7 +45,6 @@
 .. |SMCCC| replace:: :term:`SMCCC`
 .. |SoC| replace:: :term:`SoC`
 .. |SP| replace:: :term:`SP`
-.. |SPCI| replace:: :term:`SPCI`
 .. |SPD| replace:: :term:`SPD`
 .. |SPM| replace:: :term:`SPM`
 .. |SSBS| replace:: :term:`SSBS`