device/smbus_host: Declare common early SMBus prototypes

Change-Id: I1157cf391178a27db437d1d08ef5cb9333e976d0
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38233
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/northbridge/intel/pineview/raminit.c

@@ -3,6 +3,7 @@
 #include <cf9_reset.h>
 #include <device/mmio.h>
 #include <device/pci_ops.h>
+#include <device/smbus_host.h>
 #include <commonlib/helpers.h>
 #include <console/console.h>
 #include <delay.h>