x86, espfix: Move espfix definitions into a separate header file

x86, espfix: Move espfix definitions into a separate header file

commit e1fe9ed8d2a4937510d0d60e20705035c2609aea upstream.

Sparse warns that the percpu variables aren't declared before they are
defined.  Rather than hacking around it, move espfix definitions into
a proper header file.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from 3.2 commit 62358ee6bb9d3d9dd4761d39ac0e1ede9ba70b0e)
[wt: using DECLARE_PER_CPU instead of DECLARE_PER_CPU_READ_MOSTLY]
Signed-off-by: Willy Tarreau <w@1wt.eu>