libata: add ATA_HORKAGE_NOTRIM

commit 71d126fd28de2d4d9b7b2088dbccd7ca62fad6e0 upstream.

Some devices lose data on TRIM whether queued or not.  This patch adds
a horkage to disable TRIM.

tj: Collapsed unnecessary if() nesting.

Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop change to show_ata_dev_trim()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>