can: EG20T PCH: Separate Interface Register(IF1/IF2)

CAN register of Intel PCH EG20T has 2 sets of interface register.
To reduce whole of code size, separate interface register.
As a result, the number of function also can be reduced.
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>