On ESP32, due to fifo reset issue, UART2 will work incorrectly if reset the fifo of UART1(TX fifo and RX fifo). The software can workaround the RX fifo reset issue,
while the TX fifo reset issue can not. When UART2 is used and UART1 is used as the log output port, a software reset can reproduce this issue. So we should reset the UART memory
before the software reset to solve this problem.
When using DPort to read fifo, fifo_cnt is not credible, we need to calculate the real cnt based on the fifo read and write pointer. When using AHB to read FIFO, we can use fifo_cnt to indicate the data length in fifo.
