[libata] Add support for VPD page b1

SCSI VPD page b1 reports the nominal rotation speed and physical size
of the device.  Devices that conform to ATA-8 can return this information
in words 217 and 168 of the identify data.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>