introduce start function for drivers:
soem_driver::configure is used for stuff between ec_config_init and ec_config_map, start needs to be used for stuff between ec_config_map and starting
moved the ec_config_map in soem_master::configure after the driver::configure and call the new driver::start right after it. Updated el1xxx and el2xxx to use the new stuff.

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>