configs: keystone2: Do not include hardware.h

This is a hacky way to have this file included in all source files that
include common.h, instead just include from the files that need it.

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/drivers/soc/ti/keystone_serdes.c b/drivers/soc/ti/keystone_serdes.c
index 2ece1a8..0e1bf8f 100644
--- a/drivers/soc/ti/keystone_serdes.c
+++ b/drivers/soc/ti/keystone_serdes.c
@@ -8,6 +8,7 @@
 
 #include <errno.h>
 #include <common.h>
+#include <asm/io.h>
 #include <asm/ti-common/keystone_serdes.h>
 #include <linux/bitops.h>