AGESA vendorcode: Move PlatformInstall.h

All thse Option.*Install.h files are about configuring
what eventually is referenced in the final libagesa
build. It's self-contained so isolate these together
with PlatformInstall.h to hide them from rest of
the build.

Change-Id: Id9d90a3366bafc1ad01434599d2ae1302887d88c
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/21298
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/biostar/am1ml/buildOpts.c

@@ -339,4 +339,4 @@ GPIO_CONTROL   imba180_gpio[] = {
 #define DFLT_MEMORY_QUADRANK_TYPE       QUADRANK_UNBUFFERED
 #define DFLT_VRM_SLEW_RATE              (5000)
 
-#include "PlatformInstall.h"
+#include <PlatformInstall.h>