[PATCH] Beagleboneblack libdebugger support

[chrisj at rtems.org]

These patches add libdebugger support for the beagleboneblack.

Special JTAG based BBB BSP probe and configure code is needed to enable
the debug hardware in the ARM. The code requires a small hardware mod
to work as the BBB hardware by default does not enable software
debugging.

The libdebugger ARM backend has been extended to support memory mapped
modes to access the debug hardware. Special BSP hooks have been added
to aid hardware like the BBB SOC that do not provide any on chip
support to determine the memory map of SOC resources.

RPi2 crashes the debugger01.exe test which is an improvement with
these patches as it shows the ARM debugger hw is being detected and
located. There has been no testing of the code on the RPi2.

Chris