Enable multiple consoles

With a single boot image, the developer can use either the hdmi/keyboard
or the serial console. Output to both, input from either.

Bug: none
Change-Id: I53e77e260e641206df75d4bbc59838465469359a
Tracked-On: https://jira01.devtools.intel.com/browse/BP-289
Signed-off-by: Viorel Suman <viorel.suman@intel.com>