libata: Report zeroed read after TRIM and max discard size
Our current TRIM payload is a single sector that can accommodate 64 *
65535 blocks being unmapped. Report this value in the Block Limits
Maximum Unmap LBA count field.
If a storage device supports TRIM and the DRAT and RZAT bits are set,
report TPRZ=1 in Read Capacity(16).
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>