ZOOM2 Add support for debug board detection.

ZOOM2 Add support for debug board detection.

The logicpd web site is a good source for general information on this board.
Please start looking here if the below links are broken.
http://www.logicpd.com

This is a pdf of the product
http://www.logicpd.com/sites/default/files/1012659A_Zoom_OMAP34x-II_MDP_Brief.pdf

This is a pdf of the product quick start guide.
The debug board is described here.
http://support.logicpd.com/downloads/1165/

This is a wiki showing the debug board in use
https://omapzoom.org/gf/project/omapzoom/wiki/?pagename=GettingStartedWithZoomII_AKA_OMAP34XII_MDP

The zoom2 has an auxillary board that contains the serial, net, jtag and
battery simulator.  This change supports a runtime check if the debug board is
connected.

Signed-off-by: Tom Rix <Tom.Rix@windriver.com>