LU-11828 clio: fix incorrect invariant in cl_io_iter_fini()

LU-11828 clio: fix incorrect invariant in cl_io_iter_fini()

It was discovered during PFL testing that if LINVRNT() is enabled
that cl_io_iter_fini() will crash with the following backtrace:

    kernel: LustreError: 16009:0:(cl_io.c:439:cl_io_iter_fini())
            ASSERTION( io->ci_state == CIS_UNLOCKED ) failed
    kernel: cl_io_iter_fini+0x10c/0x110 [obdclass]
    kernel: cl_io_loop+0x46/0x220 [obdclass]
    kernel: cl_setattr_ost+0x1ed/0x2a0 [lustre]
    kernel: ll_setattr_raw+0x7b0/0x9a0 [lustre]
    kernel: notify_change+0x1dc/0x430
    kernel: do_truncate+0x72/0xc0
    kernel: do_sys_ftruncate+0xf5/0x160

This is due to the incorrect assumption that the ci_state will
always be CIS_UNLOCKED, but by looking at the behavior of
cl_io_loop() it can be seen that is not the case with PFL.
We do want to make sure the IO state is not in the middle of
some other action (up to CIS_IT_STARTED or CIS_IO_FINISHED or
later) when cl_io_iter_fini() is called.

Change-Id: I41c4d3ae5618d0e138f850e63edfd2dc6d4df19a
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/33915
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>