pt/test_panel_brightness: Reduce devkit brightness to 100

The '+1' is added in the assert itself now.

pytests/test_panel_brightness.py

@@ -5,9 +5,6 @@ from . import boardtype
 def test_panel_brightness():
     "Check if panel brighness range"
     path = "/sys/class/backlight/backlight-dsi"
-    if boardtype.is_librem5():
-        upper = 228
-    else:
-        upper = 101
+    upper = 228 if boardtype.is_librem5() else 100
     f = open(os.path.join(path, 'brightness'))
     assert int(f.read()) in range(0, upper + 1)