drive_opt_idx could be -1 in case error occurs inside drive_add, so the error
check should be "if (drive_opt_idx < 0)" instead of original
"if (!drive_opt_idx)".
Signed-off-by: Kaifeng Zhu <kaifeng.zhu@citrix.com>
Coverity-ID: 1055574 Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>