net: sungem: fix probe error cleanup

In the Linux kernel, the following vulnerability has been resolved: net: sungem: fix probe error cleanup gem_init_one() calls gem_remove_one() when register_netdev() fails. gem_remove_one() unregisters and frees resources owned by the net_device, including the DMA block, MMIO mapping, PCI regions, and the net_device itself. gem_init_one() then falls through to its own cleanup labels and frees the same resources again. Keep the register_netdev() error path in gem_init_one(): clear drvdata so PM/remove paths do not see a half-registered device, remove the NAPI instance added during probe, and let the existing cleanup labels release the resources once. The issue was found by a local static-analysis checker for probe error paths. The reported path was manually inspected before sending this fix. Compile-tested with CONFIG_SUNGEM=y. Runtime testing was not performed because no sungem hardware is available.