Verify that the page length matches up with the size of the data in buffer.
Verify that page length is 0x3c if the device claims SBC-3, and 0x0c if not.
If the device claims SBC-3 and if it claims UNMAP support (LBPU)
then we check that both MAXIMUM UNMAP LBA COUNT and
MAXIMUM UNMAP BLOCK DESCRIPTOR COUNT looks sane.
Sane here means >0, <1M or 0xffffffff
If the device claims SBC-3 and if it does not claim UNMAP support (LBPU)
then we check that both MAXIMUM UNMAP LBA COUNT and
MAXIMUM UNMAP BLOCK DESCRIPTOR COUNT are both 0.
