Establish a default value for XUA_MIC_FRAME_SIZE.

lib_xua/api/xua_conf_default.h

@@ -288,6 +288,13 @@
 #define PDM_MIC_INDEX           (0)
 #endif
 
+/**
+ * @brief Size of a frame of microphone data samples. Default: 1
+ */
+#ifndef XUA_MIC_FRAME_SIZE
+#define XUA_MIC_FRAME_SIZE      (1)
+#endif
+
 /**
  * @brief Enable MIDI functionality including buffering, descriptors etc. Default: DISABLED
  */