common, osd: Remove osd_read_eio_on_bad_digest config variable

common, osd: Remove osd_read_eio_on_bad_digest config variable

In order to handle erasure coded reads where additional chunks would be able to
substitute for some bad chunks, we really need to return an indication
of bad digests or incorrectly sized chunks.  We are simply using
the error return of -EIO to convey that information for future use.

Signed-off-by: David Zafman <dzafman@redhat.com>