examples/csp_arch: Drop thread test
examples/csp_arch: Drop thread test

We are dropping csp_thread support from libcsp.  Drop it from
csp_arch.

Signed-off-by: Yasushi SHOJI <afa9ca3be149447780c2f7b524d61ed3d3db63f9@spacecubics.com>

libcsp/libcsp,libcsp/libcsp