wan: lmc: Switch to using managed resources

Use managed resource functions devm_kzalloc and pcim_enable_device
to simplify error handling. Subsequently, remove unnecessary
kfree, pci_disable_device and pci_release_regions.

To be compatible with the change, various gotos are replaced with
direct returns and unneeded labels are dropped.

Also, `sc` was only being freed in the probe function and not the
remove function before the change. By using devm_kzalloc this patch
also fixes this memory leak.

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>