EMMC: adaption for ascend customized emmc card

ascend inclusion
category: feature
feature: Ascend emmc adaption
bugzilla: https://gitee.com/openeuler/kernel/issues/I4F4LL


CVE: NA

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Modified mmc ops for Ascend HiSilicon emmc card because of the
difference bwteen our emmc card and others. we used customized
property in dts to judge if it is our chips. In this patch, we
modified emmc card init process, rate setting and ext_csd register
decode/encode.

Signed-off-by: zhangguijiang <zhangguijiang@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>