CA-142337: Fix retVal of GetLunInformation

The current implementation of this method never sets the retVal to False
which leads to some spurious messages being printed on the report.

This patch sets the retVal to False when it can't find the required file
from '/dev/disk/by-scsibus/'

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>