dm: sandbox: i2c: Drop fdtdec.h header

This is not needed in this driver. Drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/sandbox_i2c.c b/drivers/i2c/sandbox_i2c.c
index 4696a1a..f5978fd 100644
--- a/drivers/i2c/sandbox_i2c.c
+++ b/drivers/i2c/sandbox_i2c.c
@@ -9,7 +9,6 @@
 #include <common.h>
 #include <dm.h>
 #include <errno.h>
-#include <fdtdec.h>
 #include <i2c.h>
 #include <asm/test.h>
 #include <dm/lists.h>