oeqa/runtime/stap: fix module name: stap-hello -> stap_hello

oeqa/runtime/stap: fix module name: stap-hello -> stap_hello

Systemtap refuses modules names like stap-hello, it says:
> ERROR: Safety pattern mismatch for -m parameter ('stap-hello' vs. '^[a-z0-9_]+$') rc=1

'stap-hello' was introduced by:
6cf4d23a2d26c2767edd93f2eb317ff759b5a992 (oeqa/runtime/stap: improve systemtap test)
and '-m parameter' regexp check was in SystemTap from 2010,
not sure how this test case ever passed after mentioned change.

Signed-off-by: Victor Kamensky <victor.kamensky7@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>