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commit 240630e6 upstream.

There have been several reports of LPM related hard freezes about once
a day on multiple Lenovo 50 series models. Strange enough these reports
where not disk model specific as LPM issues usually are and some users
with the exact same disk + laptop where seeing them while other users
where not seeing these issues.

It turns out that enabling LPM triggers a firmware bug somewhere, which
has been fixed in later BIOS versions.

This commit adds a new ahci_broken_lpm() function and a new ATA_FLAG_NO_LPM
for dealing with this.

The ahci_broken_lpm() function contains DMI match info for the 4 models
which are known to be affected by this and the DMI BIOS date field for
known good BIOS versions. If the BIOS date is older then the one in the
table LPM will be disabled and a warning will be printed.

Note the BIOS dates are for known good versions, some older versions may
work too, but we don...