ore: Don't crash on NULL bio in _clear_bio
ore: Don't crash on NULL bio in _clear_bio

In the case of target returning OSD_ERR_PRI_CLEAR_PAGES when we
only sent for attributes don't crash on NULL bio.
This is an osd-target bug but don't crash regardless

Signed-off-by: Boaz Harrosh <c7aa24d52dd751aba44a7843602dc14649cc8bce@panasas.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs