soc: imx8m: Fix match data lookup for soc device

soc: imx8m: Fix match data lookup for soc device

The i.MX8M soc device is registered via platform_device_register_simple(),
so it is not associated with a Device Tree node and the imx8m_soc_driver
has no of_match_table.

As a result, device_get_match_data() always returns NULL when probing
the soc device.

Retrieve the match data directly from the machine compatible using
of_machine_get_match_data(imx8_soc_match), which provides the correct SoC
data.

Fixes: 2524b293a59e5 ("soc: imx8m: don't access of_root directly")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Frank Li <Frank.Li@nxp.com>