Make some small improvements for arch/um/kernel/um_arch.c.
Signed-off-by: NWANG Cong <xiyou.wangcong@gmail.com>
Acked-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>