selftests/alsa: Add a few missing gitignore files

Compiled binary files should be added to .gitignore

'git status' complains:
Untracked files:
(use "git add <file>..." to include in what will be committed)
     alsa/global-timer
     alsa/utimer-test

Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Li Zhijian <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: zhijianli88

tools/testing/selftests/alsa/.gitignore

@@ -1,3 +1,5 @@
+global-timer
 mixer-test
 pcm-test
 test-pcmtest-driver
+utimer-test