AP_HAL: hwdef.py: remove unused variable initialisation

this is introduced and initialised further down in the method where it is used

libraries/AP_HAL/hwdef/scripts/hwdef.py

@@ -579,12 +579,8 @@ class HWDef:
             driver = baro.driver
             probe = baro.probe
 
-            args = ['*this']
-
             n = len(devlist)+1
 
-            args = []
-
             if driver == "DPS280":
                 # special handling for DPS280; use a probe method of
                 # the correct signature to pass into probe_spi_dev: