arm-ccn: only disable HN-I node reporting error for axm56xx

The commit da191355 ("arm-ccn: disable HN-I node reporting error
to MN node") is a workaround for the issue caused by ATF running in
axm56xx platforms. And it breaks A53 (Waco/6700) systems. So add
the condition check to fix this.

Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>