build(changelog): move mte to mte2

With commit:
https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/27122?tab=comments

FEAT_MTE is removed and we have only FEAT_MTE2, so update change log
to reflect the same.

Change-Id: I9f3bd7053f9c1fa355168968f412374e1c4937d4
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>

changelog.yaml

@@ -116,8 +116,11 @@ subsections:
       - title: Memory Partitioning and Monitoring (MPAM) Extension (FEAT_MPAM)
         scope: mpam
 
-      - title: Memory Tagging Extension
-        scope: mte
+      - title: Memory Tagging Extension2
+        scope: mte2
+
+        deprecated:
+          - mte
 
       - title: Pointer Authentication Extension
         scope: pauth