thinkpad-acpi: recognize latest V-Series using DMI_BIOS_VENDOR

In the latest V-series bios DMI_PRODUCT_VERSION does not contain
the string Lenovo or Thinkpad, but is set to the model number, this
causes the thinkpad_acpi module to fail to load. Recognize laptop
as Lenovo using DMI_BIOS_VENDOR instead, which is set to Lenovo.

Test on V490u
=============
== After the patch ==

[ 1350.295757] thinkpad_acpi: ThinkPad ACPI Extras v0.24
[ 1350.295760] thinkpad_acpi: http://ibm-acpi.sf.net/
[ 1350.295761] thinkpad_acpi: ThinkPad BIOS H7ET21WW (1.00 ), EC unknown
[ 1350.295763] thinkpad_acpi: Lenovo LENOVO, model LV5DXXX
[ 1350.296086] thinkpad_acpi: detected a 8-level brightness capable ThinkPad
[ 1350.296694] thinkpad_acpi: radio switch found; radios are enabled
[ 1350.296703] thinkpad_acpi: possible tablet mode switch found; ThinkPad in laptop mode
[ 1350.306466] thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked
[ 1350.307082] Registered led device: tpacpi::thinklight
[ 1350.307215] Registered led device: tpacpi::power
[ 1350.307255] Registered led device: tpacpi::standby
[ 1350.307294] Registered led device: tpacpi::thinkvantage
[ 1350.308160] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one
[ 1350.308333] thinkpad_acpi: Console audio control enabled, mode: monitor (read only)
[ 1350.312287] input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input14

== Before the patch ==
sudo modprobe thinkpad_acpi
FATAL: Error inserting thinkpad_acpi (/lib/modules/3.2.0-27-generic/kernel/drivers/platform/x86/thinkpad_acpi.ko): No such device

Test on B485
=============
This patch was also test in a B485 where the thinkpad_acpi module does not
have any issues loading. But, I tested it to make sure this patch does not
break on already functioning models of Lenovo products.

[13486.746359] thinkpad_acpi: ThinkPad ACPI Extras v0.24
[13486.746364] thinkpad_acpi: http://ibm-acpi.sf.net/


[13486.746368] thinkpad_acpi: ThinkPad BIOS HJET15WW(1.01), EC unknown
[13486.746373] thinkpad_acpi: Lenovo Lenovo LB485, model 814TR01
[13486.747300] thinkpad_acpi: detected a 8-level brightness capable ThinkPad
[13486.752435] thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked
[13486.752883] Registered led device: tpacpi::thinklight
[13486.752915] thinkpad_acpi: Standard ACPI backlight interface available, not loading native one
[13486.753216] thinkpad_acpi: Console audio control enabled, mode: monitor (read only)
[13486.757147] input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input15

Signed-off-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>