Andrew Turner 83724a87a4 Fix the pl011 driver to work when the uart will write in zero cycles. This
is the case, depending on the options, in some of the ARM hardware
simulators. In these cases we don't get an interrupt so will need to
schedule the task to write more data to the uart.

MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2015-03-03 09:48:19 +00:00
..