Fix maximum keycode in keyboard HID descriptor

[larsks]

The HID descriptor reported by circuitpython erroneously limited the
maximum keycode to 101, which prevented circuitpython from sending a
number of otherwise valid keycodes.

I've tested this change on my Gemma M0 and it works as expected.

Closes #2761

[larsks]

Prior to this change, the report descriptor (decoded using hidrd-convert -o xml) included:

<usage_maximum>keyboard_kb_application<!-- Keyboard Application (65h, selector) --></usage_maximum>

After this change, it includes:

<usage_maximum>keyboard_kp_hexadecimal<!-- Keypad Hexadecimal (DDh, selector) --></usage_maximum>

[dhalbert]

Thanks, you beat me to it. I was going to look at setting a country code, too (which is not done in this descriptor), because on the Mac the keyboard shows up as "unknown" the first few times. I may add a commit for that before merging.

[dhalbert]

oops, need to fix comments first

[larsks]

Oops! I have corrected the comments.

[dhalbert]

OK, thanks! Never mind about "unidentified keyboard": it's not the country code. I checked some commercial keyboards.