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>