fix unitialized memory to allow more strict build flags

[zackees]

C:\Users\niteris.platformio\packages\framework-arduinoteensy\libraries\USBHost_t36\hid.cpp: In member function 'void USBHIDParser::parse()': C:\Users\niteris.platformio\packages\framework-arduinoteensy\libraries\USBHost_t36\hid.cpp:361:20: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] usage_page = val; ^ C:\Users\niteris.platformio\packages\framework-arduinoteensy\libraries\USBHost_t36\hid.cpp: In member function 'void USBHIDParser::parse(uint16_t, const uint8_t*, uint32_t)': C:\Users\niteris.platformio\packages\framework-arduinoteensy\libraries\USBHost_t36\hid.cpp:524:37: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized] logical_max = signedval(val, tag);