And earlier commit removed the error label to two statements that
are now never reachable.  Since this code is now dead code, remove it.

Detected by CoverityScan, CID#1462409 ("Structurally dead code")

Fixes: d5d885fd ("md: introduce new personality funciton start()")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Shaohua Li <shli@fb.com>