ppc: Move reset_status to arch_global_data

Move this field into arch_global_data and tidy up.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/cpu/mpc512x/cpu.c b/arch/powerpc/cpu/mpc512x/cpu.c
index 641120f..bb03c6d 100644
--- a/arch/powerpc/cpu/mpc512x/cpu.c
+++ b/arch/powerpc/cpu/mpc512x/cpu.c
@@ -69,7 +69,7 @@
 	printf ("at %s MHz, CSB at %s MHz (RSR=0x%04lx)\n",
 		strmhz(buf1, clock),
 		strmhz(buf2, gd->arch.csb_clk),
-		gd->reset_status & 0xffff);
+		gd->arch.reset_status & 0xffff);
 	return 0;
 }