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/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 0d6122a..583424b 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -16,7 +16,6 @@
 #include "sysdep/sigcontext.h"
 #include "sysdep/barrier.h"
 #include "sigcontext.h"
-#include "mode.h"
 #include "os.h"
 
 /* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
@@ -60,14 +59,14 @@
 
 static void real_alarm_handler(int sig, struct sigcontext *sc)
 {
-	union uml_pt_regs regs;
+	struct uml_pt_regs regs;
 
 	if(sig == SIGALRM)
 		switch_timers(0);
 
 	if(sc != NULL)
 		copy_sc(&regs, sc);
-	regs.skas.is_user = 0;
+	regs.is_user = 0;
 	unblock_signals();
 	timer_handler(sig, &regs);