uml: remove code made redundant by CHOOSE_MODE removal

This patch makes a number of simplifications enabled by the removal of
CHOOSE_MODE.  There were lots of functions that looked like

	int foo(args){
		foo_skas(args);
	}

The bodies of foo_skas are now folded into foo, and their declarations (and
sometimes entire header files) are deleted.

In addition, the union uml_pt_regs, which was a union between the tt and skas
register formats, is now a struct, with the tt-mode arm of the union being
removed.

It turns out that usr2_handler was unused, so it is gone.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/um/include/task.h b/arch/um/include/task.h
index 6375ba7..3fe726b 100644
--- a/arch/um/include/task.h
+++ b/arch/um/include/task.h
@@ -3,7 +3,7 @@
 
 #include <kern_constants.h>
 
-#define TASK_REGS(task) ((union uml_pt_regs *) &(((char *) (task))[HOST_TASK_REGS]))
+#define TASK_REGS(task) ((struct uml_pt_regs *) &(((char *) (task))[HOST_TASK_REGS]))
 #define TASK_PID(task) *((int *) &(((char *) (task))[HOST_TASK_PID]))
 
 #endif