parse_hwdb: fix compatibility with pyparsing 2.4.*

pyparsing 2.3.1/2.4.0 had some changes to grouping of And matches, and as a
result we'd report 0 properties and 0 matches, and not really do any checks.

With this change we get identical behaviour for pyparsing 2.3.1, 2.4.0, 2.4.2:

$ hwdb/parse_hwdb.py
hwdb/60-evdev.hwdb: 72 match groups, 94 matches, 262 properties
hwdb/60-input-id.hwdb: 3 match groups, 3 matches, 4 properties
hwdb/60-keyboard.hwdb: 173 match groups, 256 matches, 872 properties
Keycode KBD_LCD_MENU1 unknown
Keycode KBD_LCD_MENU4 unknown
Keycode KBD_LCD_MENU2 unknown
Keycode KBD_LCD_MENU3 unknown
hwdb/60-sensor.hwdb: 101 match groups, 120 matches, 105 properties
hwdb/70-joystick.hwdb: 2 match groups, 3 matches, 2 properties
hwdb/70-mouse.hwdb: 104 match groups, 119 matches, 123 properties
hwdb/70-pointingstick.hwdb: 8 match groups, 30 matches, 11 properties
hwdb/70-touchpad.hwdb: 6 match groups, 9 matches, 6 properties

hwdb.d/parse_hwdb.py

@@ -85,7 +85,7 @@ def hwdb_grammar():
              (EMPTYLINE ^ stringEnd()).suppress())
     commentgroup = OneOrMore(COMMENTLINE).suppress() - EMPTYLINE.suppress()
 
-    grammar = OneOrMore(group('GROUPS*') ^ commentgroup) + stringEnd()
+    grammar = OneOrMore(Group(group)('GROUPS*') ^ commentgroup) + stringEnd()
 
     return grammar
 
@@ -221,7 +221,8 @@ def check_properties(groups):
             elif parsed.NAME == 'ACCEL_MOUNT_MATRIX':
                 check_one_mount_matrix(prop, parsed.VALUE)
             elif parsed.NAME.startswith('KEYBOARD_KEY_'):
-                check_one_keycode(prop, parsed.VALUE)
+                val = parsed.VALUE if isinstance(parsed.VALUE, str) else parsed.VALUE[0]
+                check_one_keycode(prop, val)
 
 def print_summary(fname, groups):
     n_matches = sum(len(matches) for matches, props in groups)