ORPSoC: Add paramers to or1200-monitor for setting name and path of log files

ORPSoC: Add paramers to or1200-monitor for setting name and path of log files

Two small patches in one to make or1200-monitor more useful outside of orpsocv2:
- Setting log path with a parameter allows more flexible directory layout
- if the plusarg "testcase" is set at runtime, this is used to set a unique
  prefix for the log files. Plusargs are currently not used in orpsocv2, so if
  it is not set, the name falls back to the value of the parameter
  TEST_NAME_STRING. The value of the parameter is set to the define
  `TEST_NAME_STRING in the test bench top levele to avoid any changes to the
  orpsocv2 scripts. With this, we can get rid of `include test-defines in
   or1200_monitor.v

Signed-off-by: Olof Kindgren <olof@opencores.org>
git-svn-id: http://opencores.org/ocsvn/openrisc/openrisc/trunk@863 04c7f051-eaf3-4997-922d-f29d9d8c0f3f