sp0256.cpp: adjust divider to achieve 10kHz sample rate [Joe Zibiciak] (#15890)

Author: tlindner

src/devices/sound/sp0256.cpp

@@ -31,7 +31,7 @@
 #define LOGFIFO(...) LOGMASKED(LOG_FIFO, __VA_ARGS__)
 
 
-#define CLOCK_DIVIDER (7*6*8)
+#define CLOCK_DIVIDER (6*4*13)
 #define HIGH_QUALITY
 
 #define SCBUF_SIZE   (4096)             /* Must be power of 2               */