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/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 0ae4eea..e183da6 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -13,7 +13,7 @@
 #include "kern_util.h"
 #include "syscall.h"
 
-void handle_syscall(union uml_pt_regs *r)
+void handle_syscall(struct uml_pt_regs *r)
 {
 	struct pt_regs *regs = container_of(r, struct pt_regs, regs);
 	long result;
@@ -37,7 +37,7 @@
 		result = -ENOSYS;
 	else result = EXECUTE_SYSCALL(syscall, regs);
 
-	REGS_SET_SYSCALL_RETURN(r->skas.regs, result);
+	REGS_SET_SYSCALL_RETURN(r->regs, result);
 
 	syscall_trace(r, 1);
 }