i386: fix section mismatch warning in intel.c

Fix following section mismatch warning:
WARNING: vmlinux.o(.text+0xc88c): Section mismatch: reference to .init.text:trap_init_f00f_bug (between 'init_intel' and 'cpuid4_cache_lookup')

init_intel are __cpuint where trap_init_f00f_bug is __init.
Fixed by declaring trap_init_f00f_bug __cpuinit.

Moved the defintion of trap_init_f00f_bug to the sole user in init.c
so the ugly prototype in intel.c could get killed.

Frank van Maarseveen <frankvm@frankvm.com> supplied the .config used
to reproduce the warning.

[ tglx: arch/x86 adaptation ]

Cc: Frank van Maarseveen <frankvm@frankvm.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>