vendorcode/amd/agesa/fam15tn: Clean #includes in public headers

Right now, coreboot code using AGESA headers can only build if all the
AGESA path are given to the compiler via the "-I" option. This is sub-
optimal, as it requires us to have every AGESA source directory
specified as a compiler include path. This pollutes our global include
paths.

We restrict the compiler include paths to only allow "AGESA_ROOT/" and
"AGESA_ROOT/Include". We then modify the AGESA headers to specify
non-local include files relative to "AGESA_ROOT/Include".

We use the convention that includes relative to the directory of the
header are included as "path/to/header.h", while includes relative to
AGESA_ROOT are included as <path/to/header.h>.

This change allows building coreboot code based on AGESA with the
limited subset of include paths, but does not allow AGESA itself to
build with this restricted subset.

Change-Id: I31102273c8caa8d6b1d80774bfd35711825bec03
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5424
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Tested-by: build bot (Jenkins)
mainboard/*/acpi/superio.asl: Use non-local inclusion syntax

Use non-local inclusion syntax over relative paths for
'drivers/pc80/ps2_controller.asl'.

Change-Id: Ie2bfa893dc268ec5118d2a9addadbc759d85d357
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/7664
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Tested-by: build bot (Jenkins)