Couple of changes in the video side.

1. Second attempt to fix the banking in the Cirrus (sigh, why doesn't banking get nulled automatically...)
2. Introduce a new timer to the 8514/A side so it won't slow the VGA clock down it was shared before.

src/include/86box/vid_8514a.h

@@ -64,6 +64,9 @@ typedef struct ibm8514_t {
     int       hwcursor_on;
     int       modechange;
 
+    uint64_t  dispontime;
+    uint64_t  dispofftime;
+
     struct {
         uint16_t subsys_cntl;
         uint16_t setup_md;