staging: most: Documentation: add information to driver_usage file

This patch updates driver_usage.txt file to reflect the latest changes
that this patch set introduces.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>