powerpc/85xx: L2 cache size wrong in 8572DS dts

It's 1MB, not 512KB.  Newer U-Boots will fix this entry, but that's no
reason to have the wrong value in the dts.
Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/boot/dts/mpc8572ds.dts

@@ -90,7 +90,7 @@ L2: l2-cache-controller@20000 {
 			compatible = "fsl,mpc8572-l2-cache-controller";
 			reg = <0x20000 0x1000>;
 			cache-line-size = <32>;	// 32 bytes
-			cache-size = <0x80000>;	// L2, 512K
+			cache-size = <0x100000>; // L2, 1M
 			interrupt-parent = <&mpic>;
 			interrupts = <16 2>;
 		};