media: staging: atomisp: Remove non-ACPI leftovers

Since all drivers are solely requiring ACPI enumeration, there is no
need to additionally check for legacy platform data or ACPI handle.

Remove leftovers from the sensors and platform code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>