Added class specific descriptor type defines with standard USB-IF element naming.

Demos/Device/ClassDriver/AudioInput/Descriptors.c

Demos/Device/ClassDriver/AudioInput/Descriptors.h

Demos/Device/ClassDriver/AudioOutput/Descriptors.c

Demos/Device/ClassDriver/AudioOutput/Descriptors.h

Demos/Device/ClassDriver/GenericHID/Descriptors.c

Demos/Device/ClassDriver/GenericHID/Descriptors.h

Demos/Device/ClassDriver/Joystick/Descriptors.c

Demos/Device/ClassDriver/Joystick/Descriptors.h

Demos/Device/ClassDriver/Keyboard/Descriptors.c

Demos/Device/ClassDriver/Keyboard/Descriptors.h

Demos/Device/ClassDriver/KeyboardMouse/Descriptors.c

Demos/Device/ClassDriver/KeyboardMouse/Descriptors.h

Demos/Device/ClassDriver/MIDI/Descriptors.c

Demos/Device/ClassDriver/MIDI/Descriptors.h

Demos/Device/ClassDriver/MassStorageKeyboard/Descriptors.c

Demos/Device/ClassDriver/MassStorageKeyboard/Descriptors.h

Demos/Device/ClassDriver/Mouse/Descriptors.c

Demos/Device/ClassDriver/Mouse/Descriptors.h

Demos/Device/ClassDriver/VirtualSerialMouse/Descriptors.c

Demos/Device/ClassDriver/VirtualSerialMouse/Descriptors.h