tests: Fix cl test api@clenqueuemigratememobjects crash.
clEnqueueMigrateMemObjects is async, calling clReleaseMemObject before it completes will cause segment fault.
So add a clfinish function after clEnqueueMigrateMemObjects could fix the issue, no more segment fault.
Signed-off-by: jiajia Qian jiajia.qian@nxp.com