arch/arm: Rename all up_*.h files to arm_*.h

Summary

The naming standard at https://cwiki.apache.org/confluence/display/NUTTX/Naming+FAQ requires that all MCU-private files begin with the name of the architecture, not up_.

This PR addresses only these name changes for the up_*.h files.  There are only three, but almost 1680 files that include them:

    up_arch.h
    up_internal.h
    up_vfork.h

The only change to the files is from including up_arch.h to arm_arch.h (for example).

The entire job required to be compatible with that Naming Convention will also require changing the naming of the up_() functions that are used only within arch/arm and board/arm.

Impact

There should be not impact of this change (other that one step toward more consistent naming).

Testing

stm32f4discovery:netnsh

boards/arm/imx6/sabre-6quad/src/imx_autoleds.c

@@ -72,7 +72,7 @@
 #include <nuttx/board.h>
 #include <arch/board/board.h>
 
-#include "up_arch.h"
+#include "arm_arch.h"
 #include "imx_gpio.h"
 #include "sabre-6quad.h"
 

boards/arm/imx6/sabre-6quad/src/imx_boardinit.c

@@ -45,7 +45,7 @@
 #include <arch/board/board.h>
 
 #include "chip.h"
-#include "up_arch.h"
+#include "arm_arch.h"
 
 #include "imx_boot.h"
 #include "sabre-6quad.h"