arm64: dts: imx8m: add NVMEM provider and consumer to read soc unique ID

In order to be able to use NVMEM APIs to read soc unique ID, add the
nvmem data cell and name for nvmem-cells to the "soc" node, and add a
nvmem node which provides soc unique ID to efuse@30350000.

Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Alice Guo <alice.guo@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>