selftest/ipc: actually test it

The ipc testcase exist in selftest but no in the TARGETS list.
Add it to the TARGETS.
Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/Makefile

@@ -6,6 +6,7 @@ TARGETS += exec
 TARGETS += firmware
 TARGETS += ftrace
 TARGETS += futex
+TARGETS += ipc
 TARGETS += kcmp
 TARGETS += lib
 TARGETS += membarrier