sceVaudio: Reserving the channel waits about 250us

On hardware sceVaudioChReserve takes ~260us once it gets past the busy
check, succeed or fail, and worse threads can run meanwhile. Releasing
takes ~25us and doesn't wait. We returned at once, which is what
audio/sceaudio/reserve's [r] markers showed; it now passes.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

test.py

@@ -156,6 +156,7 @@ tests_good = [
   "audio/blocking/oneshot",
   "audio/blocking/restlen",
   "audio/blocking/vaudio",
+  "audio/sceaudio/reserve",
   "audio/sceaudio/datalen",
   "audio/output2/changelength",
   "audio/output2/release",
@@ -531,7 +532,6 @@ tests_next = [
   "cpu/vfpu/vector",
   "cpu/vfpu/vregs",
   "audio/sceaudio/output",
-  "audio/sceaudio/reserve",
   "audio/sascore/setadsr",
   "audio/mp3/init",
   "audio/output2/frequency",