x86: reduce arch/x86/mm/ioremap.o size

> Don't we have a special section for page-aligned data so it doesn't
> waste most of two pages?

We have .bss.page_aligned and it seems appropriate to use it.

    text	   data	    bss	    dec	    hex	filename
    -   3388	   8236	      4	  11628	   2d6c	../build-32/arch/x86/mm/ioremap.o
    +   3388	     48	   4100	   7536	   1d70	../build-32/arch/x86/mm/ioremap.o

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>