platform/x86: intel-vbtn: Fix SW_TABLET_MODE always reporting 1 on the HP Pavilion 11 x360

Commit cfae58ed ("platform/x86: intel-vbtn: Only blacklist
SW_TABLET_MODE on the 9 / "Laptop" chasis-type") restored SW_TABLET_MODE
reporting on the HP stream x360 11 series on which it was previously broken
by commit de9647ef ("platform/x86: intel-vbtn: Only activate tablet
mode switch on 2-in-1's").

It turns out that enabling SW_TABLET_MODE reporting on devices with a
chassis-type of 10 ("Notebook") causes SW_TABLET_MODE to always report 1
at boot on the HP Pavilion 11 x360, which causes libinput to disable the
kbd and touchpad.

The HP Pavilion 11 x360's ACPI VGBS method sets bit 4 instead of bit 6 when
NOT in tablet mode at boot. Inspecting all the DSDTs in my DSDT collection
shows only one other model, the Medion E1239T ever setting bit 4 and it
always sets this together with bit 6.

So lets treat bit 4 as a second bit which when set indicates the device not
being in tablet-mode, as we already do for bit 6.

While at it also prefix all VGBS constant defines with "VGBS_".

Fixes: cfae58ed

 ("platform/x86: intel-vbtn: Only blacklist SW_TABLET_MODE on the 9 / "Laptop" chasis-type")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Mark Gross <mgross@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>