ub: uburma query max mtu, stat and speed attrs, then store in cdev.

driver inclusion
category: feature
bugzilla: NA
CVE: NA

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Uburma query max mtu, stat and speed attrs, then store in cdev.
All these attributes will be obtained by ubcore_query_device_status().

Signed-off-by: Guoxin Qian <qianguoxin@huawei.com>
Signed-off-by: Yizhen Fan <fanyizhen@huawei.com>