uml: const and other tidying

This patch also does some improvements for uml code.  Improvements include
dropping unnecessary cast, killing some unnecessary code and still some
constifying for pointers etc..

Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
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/sigio.c b/arch/um/os-Linux/sigio.c
index dc03e9c..7243f57 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -407,7 +407,7 @@
 	if((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
 		return -errno;
 
-	return(0);
+	return 0;
 }
 
 static void __init check_one_sigio(void (*proc)(int, int))