lib: fix fdt_parse_aclint_node()

After determining cpu_offset we have to check this variable and not
cpu_intc_offset.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>