Be more generous when parsing the report descriptor:

Be more generous when parsing the report descriptor:
- parts of the report descriptor not in a format we expect are now ignored,
  instead of preventing attachment (e.g. hypothetical multi-bit modifiers).
- modifiers beyond MAXMOD are ignored.
- keycode arrays larger than MAXKEYCODE are clamped to MAXKEYCODE instead
  of being rejected.
- multiple keycode arrays are ignored.

This should allow rogue keyboards to attach and be usable up to a certain
extent.

Adapted from a diff sent by Loganaden Velvindron (first name at gmail), who
has a keyboard which keycode array is larger than MAXKEYCODE (but, like most
if not all USB keyboards out there, can only report up to three simultaneous
keypresses anyway).