chore: update status of Cortex-X3 erratum 2615812

SDEN documentation:
https://developer.arm.com/documentation/2055130/latest

Change-Id: Ied7150bab505a743401cf4afa9a0a5f81d5fdff1
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
(cherry picked from commit f589a2a5f1b032ff3a09a419e49db0b97ccd8595)
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 2f590b2..4ee184c 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -793,7 +793,7 @@
 
 - ``ERRATA_X3_2615812``: This applies errata 2615812 workaround to Cortex-X3
   CPU. This needs to be enabled only for revisions r0p0, r1p0 and r1p1 of the
-  CPU, it is still open.
+  CPU, it is fixed in r1p2.
 
 - ``ERRATA_X3_2641945``: This applies errata 2641945 workaround to Cortex-X3
   CPU. This needs to be enabled only for revisions r0p0 and r1p0 of the CPU.