docs: driver-api: add a series of orphaned documents

There are lots of documents under Documentation/*.txt and a few other
orphan documents elsehwere that belong to the driver-API book.

Move them to their right place.

Reviewed-by: Cornelia Huck <cohuck@redhat.com> # vfio-related parts
Acked-by: Logan Gunthorpe <logang@deltatee.com> # switchtec
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/ABI/stable/sysfs-class-rfkill

@@ -1,6 +1,6 @@
 rfkill - radio frequency (RF) connector kill switch support
 
-For details to this subsystem look at Documentation/rfkill.txt.
+For details to this subsystem look at Documentation/driver-api/rfkill.rst.
 
 For the deprecated /sys/class/rfkill/*/claim knobs of this interface look in
 Documentation/ABI/removed/sysfs-class-rfkill.