IMX: MX31: Cleanup include files and drop nasty #ifdef in drivers

As exception among the i.MX processors, the i.MX31 has headers
without general names (mx31-regs.h, mx31.h instead of imx-regs.h and
clock.h). This requires several nasty #ifdef in the drivers to
include the correct header. The patch cleans up the driver and
renames the header files as for the other i.MX processors.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/board/freescale/mx31pdk/mx31pdk.c b/board/freescale/mx31pdk/mx31pdk.c
index a9f0fb4..3f291fc 100644
--- a/board/freescale/mx31pdk/mx31pdk.c
+++ b/board/freescale/mx31pdk/mx31pdk.c
@@ -26,8 +26,8 @@
 
 #include <common.h>
 #include <netdev.h>
-#include <asm/arch/mx31.h>
-#include <asm/arch/mx31-regs.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/imx-regs.h>
 
 DECLARE_GLOBAL_DATA_PTR;