iw_cxgb4: Fixes static checker warning in c4iw_rdev_open()

iw_cxgb4: Fixes static checker warning in c4iw_rdev_open()

Commit c5dfb000b904 ("iw_cxgb4: Pass qid range to user space driver")
from Dec 11, 2015, leads to the following static checker warning:

	drivers/infiniband/hw/cxgb4/device.c:857 c4iw_rdev_open()
        warn: variable dereferenced before check 'rdev->status_page'

Also we weren't deallocating ocqp pool in error path when failed to
allocate status page. Fixing it too.

Fixes: c5dfb000b904 ("iw_cxgb4: Pass qid range to user space driver")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>