arm64: dts: stratix10: socdk: drop unneeded flash address/size-cells

arm64: dts: stratix10: socdk: drop unneeded flash address/size-cells

Flash node uses single "partition" node to describe partitions, so
remove deprecated address/size-cells properties to also fix dtc W=1
warnings:

  socfpga_stratix10_socdk.dts:182.10-211.4: Warning (avoid_unnecessary_addr_size): /soc@0/spi@ff8d2000/flash@0: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>