sys/oss4/: Add some spaces in translateable strings.

Original commit message from CVS:
* sys/oss4/oss4-mixer.c:
* sys/oss4/oss4-sink.c:
* sys/oss4/oss4-source.c:
Add some spaces in translateable strings.
Fixes: #555969 #555968 #555965
3 files changed