staging: fix up speakup kobject mode

It uses the unnecessary S_IFREG bit which broke when my
stricter-checking-for-mode patch went in.

Since we're fixing it anyway, the extra level of indirection is
confusing for readers (ROOT_W == rw-r--r-- for example).

Also, many of these are other-writable.  Is that really intended?

I'll-queue-this-patch-up-in-a-bit-by: Greg KH <greg@kroah.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>