mainboard/siemens/mc_apl1: remove unnecessary header

soc/i2c.h does not need to be included in this compilation unit.

Change-Id: Ife11642d2e69af7235c93fc54bba38853b046169
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/19572
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

src/mainboard/siemens/mc_apl1/ptn3460.c

@@ -17,7 +17,6 @@
 #include <lib.h>
 #include <hwilib.h>
 #include <device/i2c.h>
-#include <soc/i2c.h>
 #include "ptn3460.h"
 
 /**