Add support for SITUA bit in Logical Block Provisioning mode page.

VMware tries to enable this bit to avoid multiple threshold notifications
in case of multiple initiators connected to the same LUN. Unfortunately
their code sends MODE SELECT(6) request with parameter length hardcoded
for the page without any thresholds. Since we have four threshold and our
page is bigger, this attempt fails, that is correct in my understanding.
So all we can do about this now is to report proper error code and hope
VMware fix their code one day.

MFC after: 2 weeks