Fix hotspare_replace_003_neg

This test contained usage errors that have been causing it to fail for an
unknown amount of time. We never noticed, because it was marked as an
expected failure. However, the underlying failure has since been fixed, so
the test can pass now that I've fixed the usage errors.

tests/sys/cddl/zfs/tests/hotspare/hotspare_replace_003_neg.ksh
Fix usage errors and improve description

tests/sys/cddl/zfs/tests/hotspare/hotspare_test.sh
Clear expected failure

Sponsored by: Spectra Logic Corp