selftests: add missing .gitignore file or entry

Only IPC selftest is missing the .gitignore file, so add it.
Also step_after_suspend_test is missing in breakpoints selftest
.gitignore file
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/breakpoints/.gitignore

 breakpoint_test
+step_after_suspend_test

tools/testing/selftests/ipc/.gitignore

+msgque_test