ub: add mmap ops support in ubcore and uburma

driver inclusion
category: feature
bugzilla: NA
CVE: NA

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In ubcore:
Add mmap ops. UBN drivers will register it to mmap physical space
like doorbell of jetty or others based on urma context.
In uburma:
Add mmap ops support in uburma file_operations.

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