fix memory handling bugs related firmware_name and firmware_cmd

Moved allocation momory code to driver probe function (svec_probe)
fw_name separated from default fw_name pointer and fixed memory
overflow. Fixed store function for firmware_cmd. Bug related to
kfree. Fixed return value to count to avoid endless loop when
returning 0 from svec_fw_cmd_program or svec_fw_cmd_reset function.
Trimming firmware_name in favor of user comfort.