audiohal: Fix typos in comments, add missing comments

These changes are in comments only, no ABI breaking changes.

Bug: 32238101
Test: make
Change-Id: Iead4ba01dae1a1c05d8fbed7f194182128e9e6ad
diff --git a/audio/effect/2.0/IPresetReverbEffect.hal b/audio/effect/2.0/IPresetReverbEffect.hal
index 2237bc4..f37e56a 100644
--- a/audio/effect/2.0/IPresetReverbEffect.hal
+++ b/audio/effect/2.0/IPresetReverbEffect.hal
@@ -31,7 +31,13 @@
         LAST = PLATE
     };
 
+    /**
+     * Sets the current preset.
+     */
     setPreset(Preset preset) generates (Result retval);
 
+    /**
+     * Gets the current preset.
+     */
     getPreset() generates (Result retval, Preset preset);
 };