libtcmu: Avoid writing uninitialized value
libtcmu: Avoid writing uninitialized value

The kernel doesn't care about the value, but in general writing garbage
should be avoided.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

agrover/tcmu-runner,superlibj/tcmu-runner,open-iscsi/tcmu-runner,liuy/tcmu-runner,open-iscsi/tcmu-runner,lxbsz/tcmu-runner,yasker/tcmu-runner,JefferyHu/tcmu-runner