CIFS: Use invalidate_inode_pages2 instead of invalidate_remote_inode (try #4)

Use invalidate_inode_pages2 that don't leave pages even if shrink_page_list()
has a temp ref on them. It prevents a data coherency problem when
cifs_invalidate_mapping didn't invalidate pages but the client thinks that a data
from the cache is uptodate according to an oplock level (exclusive or II).

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>