x86: clean up old gcc warnings

gcc 3.2.2 reports:

In file included from /usr/src/all/linux-next/arch/x86/include/asm/page.h:8,
                 from /usr/src/all/linux-next/arch/x86/include/asm/processor.h:18,
                 from /usr/src/all/linux-next/arch/x86/include/asm/atomic_32.h:6,
                 from /usr/src/all/linux-next/arch/x86/include/asm/atomic.h:2,
                 from include/linux/crypto.h:20,
                 from arch/x86/kernel/asm-offsets_32.c:7,
                 from arch/x86/kernel/asm-offsets.c:2:
/usr/src/all/linux-next/arch/x86/include/asm/page_types.h:54: warning: parameter has incomplete type
/usr/src/all/linux-next/arch/x86/include/asm/page_types.h:56: warning: parameter has incomplete type
In file included from /usr/src/all/linux-next/arch/x86/include/asm/page.h:8,
                 from /usr/src/all/linux-next/arch/x86/include/asm/processor.h:18,
                 from include/linux/prefetch.h:14,
                 from include/linux/list.h:6,
                 from include/linux/module.h:9,
                 from init/main.c:13:
/usr/src/all/linux-next/arch/x86/include/asm/page_types.h:54: warning: parameter has incomplete type
/usr/src/all/linux-next/arch/x86/include/asm/page_types.h:56: warning: parameter has incomplete type

This is a bogus warning, but moving the pat-related functions
into asm/pat.h and including asm/pgtable_types.h should fix it.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Signed-off-by: Ingo Molnar <mingo@elte.hu>