Slow down DDC I2C bus using a RiseFallTime of 20us for old monitors.

This time value makes the bus run slowly enough for even the least reliable
of monitors. Thanks to Pavel Troller for finding the necessary change.

hw/xfree86/ddc/xf86DDC.c

@@ -337,6 +337,12 @@ DDCRead_DDC2(int scrnIndex, I2CBusPtr pBus, int start, int len)
     unsigned char *R_Buffer;
     int i;
     
+    /*
+     * Slow down the bus so that older monitors don't 
+     * miss things.
+     */
+    pBus->RiseFallTime = 20;
+    
     if (!(dev = xf86I2CFindDev(pBus, 0x00A0))) {
 	dev = xf86CreateI2CDevRec();
 	dev->DevName = "ddc2";