[CIFS] Fix cifs trying to write to f_ops

patch 2ea55c01e0c5dfead8699484b0bae2a375b1f61c fixed CIFS clobbering the
global fops structure for some per mount setting, by duplicating and having
2 fops structs. However the write to the fops was left behind, which is a
NOP in practice (due to the fact that we KNOW the fops has that field set
to NULL already due to the duplication). So remove it... In addition, another
instance of the same bug was forgotten in november.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>