platform/x86: dell-laptop: Add 2-in-1 devices to the DMI whitelist

SMBIOS 3.0.0 Specification introduced new Chassis Types field values for
2-in-1 devices like tablets, convertibles and detachables. Dell's
Inspiron 2-in-1 and XPS 2-in-1 fall into this category and they have to
be added to the DMI whitelist, so rfkill and backlight can be controlled
for them as for other laptops.

Signed-off-by: Alexander Abrosimov <alexander.n.abrosimov@gmail.com>
Reviewed-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>