CIFS: Move locks to cifsFileInfo structure

CIFS brlock cache can be used by several file handles if we have a
write-caching lease on the file that is supported by SMB2 protocol.
Prepate the code to handle this situation correctly by sorting brlocks
by a fid to easily push them in portions when lease break comes.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>