pch_can: Fix endianness issue

there is endianness issue both Tx and Rx.
Currently, data is set like below.
Register:
MSB--LSB
x x D0 D1
x x D2 D3
x x D4 D5
x x D6 D7

But Data to be sent must be set like below.
Register:
MSB--LSB
x x D1 D0
x x D3 D2
x x D5 D4
x x D7 D6  (x means reserved area.)

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>