Template:CC31xx & CC32xx PLG common section uart config

The UART configuration is as follows:
 * Baud rate: 921600
 * Data bits: 8 bits
 * Flow control: None
 * Parity: None
 * Stop bits: 1
 * Polarity: Positive

The CMOS logic level specifications for the UART can be found in the CC datasheet under Electrical Characteristics: http://www.ti.com/lit/ds/symlink/cc.pdf