macfb: allow larger write accesses to the DAFB_LUT register

The original tests with MacOS showed that only the bottom 8 bits of the DAFB_LUT
register were used when writing to the LUT, however A/UX performs some of its
writes using 4 byte accesses. Expand the address range for the DAFB_LUT register
so that different size accesses write the correct value to the color_palette
array.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-ID: <20231026085650.917663-4-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/display/macfb.c

@@ -37,7 +37,7 @@
 #define DAFB_INTR_STAT      0x108
 #define DAFB_INTR_CLEAR     0x10c
 #define DAFB_LUT_INDEX      0x200
-#define DAFB_LUT            0x213
+#define DAFB_LUT            0x210
 
 #define DAFB_INTR_VBL   0x4
 
@@ -586,8 +586,8 @@ static void macfb_ctrl_write(void *opaque,
     case DAFB_LUT_INDEX:
         s->palette_current = (val & 0xff) * 3;
         break;
-    case DAFB_LUT:
-        s->color_palette[s->palette_current] = val;
+    case DAFB_LUT ... DAFB_LUT + 3:
+        s->color_palette[s->palette_current] = val & 0xff;
         s->palette_current = (s->palette_current + 1) %
                              ARRAY_SIZE(s->color_palette);
         if (s->palette_current % 3) {