device: Fix leak if probe groups are created.
serial: Fix leak in serial_open.

A new sp_port is created every time we call serial_open (sp_get_port_by_name
implicitly creates one for us), so free it every time we call serial_close.
serial: Use new sp_set_config instead of sp_set_params.
Use new sp_port_config fields.
serial.c: Minor cosmetic fix.
gmc_mh_1x_2x: Inital driver skeleton.