[U-Boot] RFC: i.MX UART failures with baud-rate mis-match

[Eric Nelson]

We've identified an issue with i.MX UARTs which causes an infinite
stream of input characters when certain input characters with an
incorrect baud rate are received.

The details and a couple of ways to reproduce are in this thread
on i.MX Community:
	https://community.freescale.com/message/403254

We'd like to get some feedback from other users of i.MX to see whether
the problem exists on especially i.MX51 and i.MX3x.

The easiest way to reproduce the problem is to apply patch 1 in
the series, change a serial console to 19200, and send a 
lower-case 'b' to the serial port at 115200 baud:

	U-Boot > setenv baudrate 19200
	## Switch baudrate to 19200 bps and press ENTER ...


	... hit a 'b' at 115200 and you should see a spew of
	garbage.

	... hit an 'a' and the spew should stop.

This has been repeated on i.MX6Q, i.MX6S and i.MX53-based boards.

Patch 2 of 2 should resolve the issue.