Optimize vendor/product description string display code in MassStorageHost.

Remove all Host mode class demos other than the CDCHost class driver demo, so that they can be re-added as they are made once the host mode class framework is designed.

Fixed USB_Host_SendControlRequest() not re-suspending the USB bus when initial device ready-wait fails.

Fixed USB Pad regulator not being disabled on some AVR models when the USB_OPT_REG_DISABLED option is used.