board: cogent: include header files in a more natural way

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/board/cogent/mb.c b/board/cogent/mb.c
index 603f123..3eea47d 100644
--- a/board/cogent/mb.c
+++ b/board/cogent/mb.c
@@ -6,11 +6,11 @@
  */
 
 #include <common.h>
-#include <board/cogent/dipsw.h>
-#include <board/cogent/lcd.h>
-#include <board/cogent/rtc.h>
-#include <board/cogent/par.h>
-#include <board/cogent/pci.h>
+#include "dipsw.h"
+#include "lcd.h"
+#include "rtc.h"
+#include "par.h"
+#include "pci.h"
 
 /* ------------------------------------------------------------------------- */