LU-5260 llite: removing ll_cl_context when error occurs

LU-5260 llite: removing ll_cl_context when error occurs

The bug is imported from commit f1b9122c of LU-5108.
It should have removed ll_cl_context from the list if failed to take
lli_write_mutex at:

	if ((iot == CIT_WRITE) &&
	    !(cio->cui_fd->fd_flags & LL_FILE_GROUP_LOCKED)) {
		if (mutex_lock_interruptible(&lli->lli_write_mutex))
			GOTO(out, result = -ERESTARTSYS);

Revise it to add ll_context right before cl_io_loop.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I6532bb8919c13692bd0ceb1ba0d755c1417e5095
Reviewed-on: http://review.whamcloud.com/10955
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>