arm64: dts: ls1028a: add missing CAN nodes

[ Upstream commit 04fa4f03 ]

The LS1028A has two FlexCAN controller. These are compatible with
the ones from the LX2160A. Add the nodes.

The first controller was tested on the Kontron sl28 board.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>