LU-15637 llite: Fix use of uninitialized fields

LU-15637 llite: Fix use of uninitialized fields

We use data from ci_rw to set io_start_index and
io_end_index, which is a problem for mmap because mmap does
not use ci_rw.

When ci_rand_read is set or readahead is disabled, we use
these values to decide how much data to read.

ci_rw is uninitialized, and if the values are non-zero,
we may try to read data beyond the locks we took for our
I/O.

If there is no lock (either because there was never one or
it was cancelled), this results in an LBUG in
osc_req_attr_set when it verifies the pages are covered by
a lock.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: If7c8d2eb87a28bf76a6f959e7be7bf636c887cfe