common: Move hang() to the same header as panic()

At present panic() is in the vsprintf.h header file. That does not seem
like an obvious choice for hang(), even though it relates to panic(). So
let's put hang() in its own header.

Signed-off-by: Simon Glass <sjg@chromium.org>
[trini: Migrate a few more files]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-imx/mx6/ddr.c b/arch/arm/mach-imx/mx6/ddr.c
index 8ed8b79..4396880 100644
--- a/arch/arm/mach-imx/mx6/ddr.c
+++ b/arch/arm/mach-imx/mx6/ddr.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <hang.h>
 #include <linux/types.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/mx6-ddr.h>
diff --git a/arch/arm/mach-imx/spl.c b/arch/arm/mach-imx/spl.c
index 5a6493a6..87dbdf3 100644
--- a/arch/arm/mach-imx/spl.c
+++ b/arch/arm/mach-imx/spl.c
@@ -7,6 +7,7 @@
  */
 
 #include <common.h>
+#include <hang.h>
 #include <asm/io.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/sys_proto.h>