x86: coding style fixes in arch/x86/lib/io_64.c

This simple patch makes the file error free (according to
checkpatch.pl)

no code changed:

arch/x86/lib/io_64.o:
   text    data     bss     dec     hex filename
    308       0       0     308     134 io_64.o.before
    308       0       0     308     134 io_64.o.after
md5:
3c64f9ed83d091678e849b36ca27bee3  io_64.o.before.asm
3c64f9ed83d091678e849b36ca27bee3  io_64.o.after.asm

Signed-off-by: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>