armv7: ls102xa: add errata ID A-008646 for workaround

The patch adds an errata ID A-008646 for workaround
to provide more information by errata ID.

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/arch/arm/cpu/armv7/ls102xa/ls102xa_psci.c b/arch/arm/cpu/armv7/ls102xa/ls102xa_psci.c
index 00b6ad4..86693ed 100644
--- a/arch/arm/cpu/armv7/ls102xa/ls102xa_psci.c
+++ b/arch/arm/cpu/armv7/ls102xa/ls102xa_psci.c
@@ -68,9 +68,10 @@
 
 	ippdexpcr0 = in_be32(&rcpm->ippdexpcr0);
 	/*
-	 * Workaround: There is bug of register ippdexpcr1, when read it always
-	 * returns zero, so its value is saved to a scrachpad register to be
-	 * read, that is why we don't read it from register ippdexpcr1 itself.
+	 * Workaround of errata A-008646
+	 * Errata states that read to register ippdexpcr1 always returns
+	 * zero irrespective of what value is written into it. So its value
+	 * is first saved to a spare register and then read from it
 	 */
 	ippdexpcr1 = in_be32(&scfg->sparecr[7]);
 	out_be32(&rcpm->ippdexpcr1, ippdexpcr1);