powerpc: Fix old bug in prom_init setting of the color

We have an array of 16 entries and a loop of 32 iterations... oops.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/prom_init.c

@@ -2080,7 +2080,7 @@ static void __init prom_check_displays(void)
 		/* Setup a usable color table when the appropriate
 		 * method is available. Should update this to set-colors */
 		clut = RELOC(default_colors);
-		for (i = 0; i < 32; i++, clut += 3)
+		for (i = 0; i < 16; i++, clut += 3)
 			if (prom_set_color(ih, i, clut[0], clut[1],
 					   clut[2]) != 0)
 				break;