uml: tidy helper code

Style fixes to arch/um/os/helper.c and tidying up the breakpoint fix a
bit.

helper.c gets all the usual style fixes -
	 updated copyright
	 all printks get severities

Also -
	 errval changes to err in helper_child
	 fixed an obsolete comment
	 run_helper was killing a child process which is guaranteed to
be dead or dying anyway

Removed the nohang and pname arguments from helper_wait and fixed the
declaration and callers.  nohang was used only in the slirp driver and
I don't think it was needed.  I think pname was a bit of overkill in
putting out an error message when something goes wrong.

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>