cifs: remove some camelCase and also some static build warnings

Remove warnings for five global variables. For example:
  fs/cifs/cifsglob.h:1984:24: warning: symbol 'midCount' was not declared. Should it be static?

Also change them from camelCase (e.g. "midCount" to "mid_count")

Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>