eth: dpaa2-mac: remove a dead-code NULL check on fwnode parent

Since commit 4e30e98c4b4c ("dpaa2-mac: return -EPROBE_DEFER from dpaa2_mac_open in case the fwnode is not set")
@parent can't be NULL after the if. It's either the address
of the ->fwnode of @dpmacs or @fwnode in case of ACPI.

Signed-off-by: Jakub Kicinski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c

···
 		return ERR_PTR(-EPROBE_DEFER);
 	}
 
-	if (!parent)
-		return NULL;
-
 	fwnode_for_each_child_node(parent, child) {
 		err = -EINVAL;
 		if (is_acpi_device_node(child))