chore: rename Makalu ELP to Cortex-X3

The Cortex-X3 cpu port was developed before its public release when it
was known as Makalu ELP. Now that it's released we can use the official
product name.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Iebb90cf2f77330ed848a3d61c5f6928942189c5a
diff --git a/docs/plat/arm/tc/index.rst b/docs/plat/arm/tc/index.rst
index ae2b836..df1847d 100644
--- a/docs/plat/arm/tc/index.rst
+++ b/docs/plat/arm/tc/index.rst
@@ -18,7 +18,7 @@
 is the CPUs supported as below:
 
 -  TC0 has support for Cortex A510, Cortex A710 and Cortex X2.
--  TC1 has support for Cortex A510, Cortex Makalu and Cortex Makalu ELP.
+-  TC1 has support for Cortex A510, Cortex Makalu and Cortex X3.
 -  TC2 has support for Hayes and Hunter Arm CPUs.