verify: disable header seed check for verify_only jobs

verify: disable header seed check for verify_only jobs

For the invoked verify_only job, header seed can match only if it
exactly matches the original write job. This means either randrepeat
should be true, or we must use the same randseed which was used with the
original write job. After write the verify_only workload shouldn't be
changed from sequential to random or vice versa.

Considering these constraints disable verify_header_seed for verify_only
jobs. Users will still be able to enable header seed checking if they
explicitly set the verify_header_sequence option.

Signed-off-by: Ankit Kumar <ankit.kumar@samsung.com>