Fixed typo in exception string

Fixed typo in the string returned by the __init__
exception

Signed-off-by: Alejandro Hernandez <ajhernandez@ti.com>
Refactored stp to only use three attr in bench entries

Refactored stp to onlu use init_info, params and
driver_class_name as configurable properties in bench entries.
Doing this avoid having to change the EquipmentInfo class every
time new information is needed in the bench to run a test.

Signed-off-by: Alejandro Hernandez <ajhernandez@ti.com>
Added devantech and TI USB switch drivers

Signed-off-by: Alejandro Hernandez <ajhernandez@ti.com>