Introduce an `include` directory for header files

Move all header files to the new `include` directory.
Adapt include directives and build systems to the new directory.

Change-Id: Iaddd6bbfa0624b166d422f665877f096983bf4cf
Signed-off-by: Felix Singer <felix.singer@secunet.com>
Signed-off-by: Thomas Heijligen <thomas.heijligen@secunet.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/58622
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/72322
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
diff --git a/platform/endian_big.c b/platform/endian_big.c
index 5d65500..6541a83 100644
--- a/platform/endian_big.c
+++ b/platform/endian_big.c
@@ -15,7 +15,7 @@
  * GNU General Public License for more details.
  */
 
-#include "../platform.h"
+#include "platform.h"
 
 /* convert cpu native endian to little endian */
 ___return_swapped(cpu_to_le, 8)
diff --git a/platform/endian_little.c b/platform/endian_little.c
index b7c0068..aeb9d57 100644
--- a/platform/endian_little.c
+++ b/platform/endian_little.c
@@ -15,7 +15,7 @@
  * GNU General Public License for more details.
  */
 
-#include "../platform.h"
+#include "platform.h"
 
 /* convert cpu native endian to little endian */
 ___return_same(cpu_to_le, 8)
diff --git a/platform/memaccess.c b/platform/memaccess.c
index 44ef410..8368121 100644
--- a/platform/memaccess.c
+++ b/platform/memaccess.c
@@ -15,7 +15,7 @@
  * GNU General Public License for more details.
  */
 
-#include "../platform.h"
+#include "platform.h"
 
 /*
  * macro to return endian aware read function
diff --git a/platform/pci.h b/platform/pci.h
deleted file mode 100644
index 2a524b2..0000000
--- a/platform/pci.h
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * This is a wrapper for libpci.
- * ...
- */
-
-
-#ifndef __PLATFORM_PCI_H__
-#define __PLATFORM_PCI_H__
-
-/*
- * An old libpci version seems to use the variable name "index" which triggers
- * shadowing warnings on systems which have the index() function in a default
- * #include or as builtin.
- */
-#define index shadow_workaround_index
-
-#if defined (PCIUTILS_PCI_H)
-#include <pci.h>
-#else
-#include <pci/pci.h>
-#endif
-
-#undef index
-
-#endif /* __PLATFORM_PCI_H__ */