x86: uaccess: return value of __{get|put}_user() can be int

Impact: cleanup

The type of return value of __{get|put}_user() can be int.
There is no user to refer the return value of __{get|put}_user() as long.
This reduces code size a bit on 64-bit.

 $ size vmlinux.*
     text	   data	    bss	    dec	    hex	filename
  4509265	 479988	 673588	5662841	 566879	vmlinux.new
  4511462	 479988	 673588	5665038	 56710e	vmlinux.old

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>