arc: move openocd_dbg section

Its current placement was splitting the vector table in half.
Move to rodata, a better place for it. There's no requirement for
it to be in the text section.

Change-Id: I67724b2a26a9cb62c2ccd473cb54c53e4f74dc32
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>