can: EG20T PCH: add prefix to macro

For easy to readable/identifiable, add prefix "PCH_" to all of #define macros.
Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>