platform: x86: dell-smo8800: Dell Latitude freefall driver (ACPI SMO8800/SMO8810)

This acpi driver provide supports for freefall sensors SMO8800/SMO8810 which
can be found on Dell Latitude laptops. Driver register /dev/freefall misc
device which has same interface as driver hp_accel freefall driver. So any
existing applications for HP freefall sensor /dev/freefall will work for with
this new driver for Dell Latitude laptops too.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Cc: Sonal Santan <sonal.santan@gmail.com>
Tested-By: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Acked-By: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>