fix review feedback from FoamyGuy - get code closer to Bosch reference.

Author: CTho9305

adafruit_bme680.py

@@ -602,7 +602,7 @@ def _calc_gas_wait(self, dur: int) -> int:
         factor: int = 0
         durval: int = 0xFF  # Max duration
 
-        if dur > 0xFC0:
+        if dur >= 0xFC0:
             return durval
         while dur > 0x3F:
             dur = dur / 4