m68k: merge MMU and non MMU versions of system.h

The non-MMU m68k targets can use the same asm/system.h as the MMU
targets. So switch the current system_mm.h to be system.h and remove
system_no.h.

The assembly support code for the non-MMU resume functions needs to
be modified to match the now common switch_to() macro. Specifically
this means correctly saving and restoring the status flags in the case
of the ColdFire resume, and some reordering of the code to not use
registers before they are saved or after they are restored.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
diff --git a/arch/m68k/platform/68328/entry.S b/arch/m68k/platform/68328/entry.S
index f68dce7..4ed7a65 100644
--- a/arch/m68k/platform/68328/entry.S
+++ b/arch/m68k/platform/68328/entry.S
@@ -241,22 +241,21 @@
 
 /*
  * Beware - when entering resume, prev (the current task) is
- * in a0, next (the new task) is in a1,so don't change these
+ * in a0, next (the new task) is in a1, so don't change these
  * registers until their contents are no longer needed.
  */
 ENTRY(resume)
 	movel	%a0,%d1				/* save prev thread in d1 */
 	movew	%sr,%a0@(TASK_THREAD+THREAD_SR)	/* save sr */
-	movel	%usp,%a2			/* save usp */
-	movel	%a2,%a0@(TASK_THREAD+THREAD_USP)
-
 	SAVE_SWITCH_STACK
 	movel	%sp,%a0@(TASK_THREAD+THREAD_KSP) /* save kernel stack */
+	movel	%usp,%a3			/* save usp */
+	movel	%a3,%a0@(TASK_THREAD+THREAD_USP)
+
+	movel	%a1@(TASK_THREAD+THREAD_USP),%a3 /* restore user stack */
+	movel	%a3,%usp
 	movel	%a1@(TASK_THREAD+THREAD_KSP),%sp /* restore new thread stack */
 	RESTORE_SWITCH_STACK
-
-	movel	%a1@(TASK_THREAD+THREAD_USP),%a0 /* restore user stack */
-	movel	%a0,%usp
 	movew	%a1@(TASK_THREAD+THREAD_SR),%sr	/* restore thread status reg */
 	rts