macfb: rename DAFB_RESET to DAFB_LUT_INDEX

When A/UX uses the MacOS Device Manager Status (GetEntries) call to read the
contents of the CLUT, it is easy to see that the requested index is written to
the DAFB_RESET register. Update the palette_current index with the requested
value, and rename it to DAFB_LUT_INDEX to reflect its true purpose.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-ID: <20231026085650.917663-3-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/display/macfb.c

@@ -36,7 +36,7 @@
 #define DAFB_INTR_MASK      0x104
 #define DAFB_INTR_STAT      0x108
 #define DAFB_INTR_CLEAR     0x10c
-#define DAFB_RESET          0x200
+#define DAFB_LUT_INDEX      0x200
 #define DAFB_LUT            0x213
 
 #define DAFB_INTR_VBL   0x4
@@ -583,8 +583,8 @@ static void macfb_ctrl_write(void *opaque,
         s->regs[DAFB_INTR_STAT >> 2] &= ~DAFB_INTR_VBL;
         macfb_update_irq(s);
         break;
-    case DAFB_RESET:
-        s->palette_current = 0;
+    case DAFB_LUT_INDEX:
+        s->palette_current = (val & 0xff) * 3;
         break;
     case DAFB_LUT:
         s->color_palette[s->palette_current] = val;