[BUILD] Correct inplace build for examples
[lm4f] Remove usb cdc definitions moved to library

Requires a library bump to match
[stm32f4] USB CDC-ACM to USART w/ rs485

Based on the existing lm4f implementation of cdc-acm to uart, and the existing
f4 cdc-acm loop back examples, this includes the ST appnote code on managing
rs485 signals