libata: check for trusted computing in IDENTIFY DEVICE data

ATA-8 and later mirrors the TRUSTED COMPUTING SUPPORTED bit in word 48 of
the IDENTIFY DEVICE data.  Check this before issuing a READ LOG PAGE
command to avoid issues with buggy devices.  The only downside is that
we can't support Security Send / Receive for a device with an older
revision due to the conflicting use of this field in earlier
specifications.

tj: The reason we need this is because some devices which don't
    support READ LOG PAGE lock up after getting issued that command.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>