tracing: Add SPDX license GPL-2.0 license identifier to inter-event testcases

Apparently this directory was missed in the license cleanup process -
add the missing identifiers to the trigger/inter-event test cases.

Link: http://lkml.kernel.org/r/6f9828c2cfb0b378ebd217a39a1b44f063fc17fb.1550100284.git.tom.zanussi@linux.intel.comSigned-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-extended-error-support.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test extended error support
 
 

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-field-variable-support.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test field variable support
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-inter-event-combined-hist.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event combined histogram trigger
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-multi-actions-accept.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test multiple actions on hist trigger
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmatch-action-hist.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmatch action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmatch-onmax-action-hist.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmatch-onmax action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-onmax-action-hist.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test inter-event histogram trigger onmax action
 
 fail() { #msg

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-synthetic-event-createremove.tc

 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
 # description: event trigger - test synthetic event create remove
 
 fail() { #msg