libata: expose pm qos flags for ata device

libata: expose pm qos flags for ata device

Expose pm qos flags to user space so that user has a chance to disable
ZPODD feature, if he/she has a broken platform or devices or simply does
not like this feature.

This flag is exposed to user space only for ZPODD devices.

Due to this flag, it is possible the ODD is ZP ready but we didn't power
it off. So the zp_ready flag will need to be cleared whenever we found
the ODD is not in ZP ready state. Previously, once zp_ready is set, the
ODD will always be powered off and the flag will be cleared in
post_poweron. But this is no longer the case now.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>