AMD Steppe Eagle: Add binary PI vendorcode files

Add all of the PI source that will remain part of coreboot to
build with a binary AGESA PI BLOB.  This includes the gcc
makefiles, some Kconfig, and the AGESA standard library
functions.

Change vendorcode Makefile and Kconfig so that they can compile
AMD library files and use headers from outside the coreboot/src
tree.

The AGESA dispatcher is built using its own rules rather than
generic library generation rules in coreboot/Makefile and
coreboot/Makefile.inc.  The AGESA source files are initially
copied from whereever they live into coreboot/build/agesa.
They are compiled from there.  The binary PI directory has a
mandatory structure that places the AGESA BLOB into the same
directory as the support headers.  These will nominally be
placed in the 3rdparty directory in coreboot.org.

The copy commands that were added to the the vendorcode
Makefile.inc ensure that only one thread will operate on each
source file by using a macro to generate the copy targets.
After the change, each copy target will operate on exactly one
source file.

Due to API issues, coreboot has no way to control the IMC to set up
fan control.  Set a Kconfig flag that removes the ability to install
an IMC BLOB into CBFS.

Change-Id: I050b72a19086aaeba6cb65ce165297b10e3cfc45
Signed-off-by: Bruce Griffith <Bruce.Griffith@se-eng.com>
Reviewed-on: http://review.coreboot.org/6595
Tested-by: build bot (Jenkins)
Reviewed-by: WANG Siyuan <wangsiyuanbuaa@gmail.com>
Reviewed-by: Zheng Bao <zheng.bao@amd.com>
diff --git a/src/vendorcode/amd/Makefile.inc b/src/vendorcode/amd/Makefile.inc
index 2897ff2..8cce5e6 100644
--- a/src/vendorcode/amd/Makefile.inc
+++ b/src/vendorcode/amd/Makefile.inc
@@ -1,2 +1,3 @@
+subdirs-y += pi
 subdirs-y += agesa
 subdirs-y += cimx