ARM: dts: imx6ul: change operating-points to uint32-matrix

ARM: dts: imx6ul: change operating-points to uint32-matrix

operating-points is a uint32-matrix as per opp-v1.yaml. Change it
accordingly. While at it, change fsl,soc-operating-points as well,
although there is no bindings file (yet). But they should have the same
format. Fixes the dt_binding_check warning:
cpu@0: operating-points:0: [696000, 1275000, 528000, 1175000, 396000,
1025000, 198000, 950000] is too long
cpu@0: operating-points:0: Additional items are not allowed (528000,
1175000, 396000, 1025000, 198000, 950000 were unexpected)

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>