USB keyboard right shift key was ignored

This is the same problem and fix released into the Arduino Zero USBHost library.

https://github.com/arduino/ArduinoCore-samd/pull/87

KeyboardReportParser::OemToAscii() returned lower case characters even when the right side shift key is pressed. The left side shift key works fine.

The fix is in the following pull request.
https://github.com/arduino-libraries/USBHost/pull/10
