Move eSPI files to board common code

The eSPI logic is the same for all TGL boards using it. None of it is
moved to IT5570E due to the call to power_cpu_reset().

Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/board/system76/lemp10/include/board/espi.h

@@ -1,12 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-only
-
-#ifndef _BOARD_ESPI_H
-#define _BOARD_ESPI_H
-
-#include <ec/espi.h>
-
-void espi_init(void);
-void espi_reset(void);
-void espi_event(void);
-
-#endif // _BOARD_ESPI_H