nios2: add flashing/debug scripts

For the moment, NIOS2_CPU_SOF must be set with the path to the
CPU configuration. We are checking with Altera on whether we
can directly check in the binary to the source tree.

These scripts depend on tools provided by the Altera Quartus
Prime Lite Edition. This is available for free but requires
registration on Altera's website to obtain.

Change-Id: Ia6cb6c9e43c3e141807a887cb25c47b370a7d8e9
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>