[ARM] pxa: update cpu_is_xsc3() to include Marvell CPUID

CPU id is changed in Marvell chip. So update the code in cpu_is_xsc3().

Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>