ctld(8): Fix MaxBurstLength negotiation.

[np]

Summary

The target must reply with the selected value of MaxBurstSize instead of
just echoing back the initiator's offered value.

[mav]

It makes sense, though barely change anything.

[np]

In D7278#151397, @mav wrote:

It makes sense, though barely change anything.

If the initiator has a higher limit than the FreeBSD ctld target then the target will internally lower its MaxBurstLength but echo back the higher value to the initiator, causing the two sides to disagree on what MaxBurstLength really is.

[mav]

In D7278#151489, @np wrote:

In D7278#151397, @mav wrote:

It makes sense, though barely change anything.

If the initiator has a higher limit than the FreeBSD ctld target then the target will internally lower its MaxBurstLength but echo back the higher value to the initiator, causing the two sides to disagree on what MaxBurstLength really is.

Sure, I just wanted to say that at this point it is not probably breaking anything. CTL uses this value only to limit transmissions, so limiting lower then remote size expects is not a problem. For receive CTL has no any limit now, so it also don't harm. But yes, it should be fixed.