x86: Axe the lightly-used cpu_has_pae

cpu_has_pae is only referenced in one place: the X86_32 kexec
code (in a file not even built on 64-bit).  It hardly warrants
its own macro, or the trouble we go to ensuring that it can't
be called in X86_64 code.

Axe the macro and replace it with a direct cpu feature check.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/r/20140911211511.AD76E774@viggo.jf.intel.com


Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>