tcl: Support for Analog Devices ADSP-SC58x / ADSP-SC584-EZBRD

tcl: Support for Analog Devices ADSP-SC58x / ADSP-SC584-EZBRD

The original script was broken by changes to the Cortex-A code.  The
recent introduction of the mem_ap target provided a new mechanism to
allow the script to be fixed.  This also adds an example board script
for the ADSP-SC584-EZBRD.

Change-Id: I36bc1ac6b6c036539f4175f1e65223ba10a35355
Signed-off-by: Peter Lawrence <majbthrd@gmail.com>
Reviewed-on: http://openocd.zylin.com/4855
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>