net: tsec: Support <reg> property from the subnode "queue-group"

net: tsec: Support <reg> property from the subnode "queue-group"

At present the tsec driver uses a non-standard DT bindings to get
its <reg> base / size. The upstream Linux kernel seems to require
the <reg> base / size to be put under a subnode of the eTSEC node
with a name prefix "queue-group". This is not documented in the
kernel DT bindings, but it looks every dtsi file that contains the
eTSEC node was written like this.

This commit updates the tsec driver to handle this case.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>