ARM: dts: imx6qdl-sabreauto: add flexcan support

The flexcan1 is pin conflict with fec. User would make flexcan1 enabled
with fec disabled to use CAN.

Signed-off-by: Aisheng Dong <aisheng.dong@nxp.com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>