i.MX6DQPlus support sata interface, so not return failure
when CPU is i.MX6DQPlus.

In this patch, also use simpler runtime cpu dections macros to replace
is_cpu_type.

Signed-off-by: Peng Fan <van.freenix@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tang Yuantian <Yuantian.Tang@freescale.com>
Cc: Shaohui Xie <Shaohui.Xie@freescale.com>
Cc: Bin Meng <bmeng.cn@gmail.com>