net: hip04: fix RX buffer leak on build_skb failure

In the Linux kernel, the following vulnerability has been resolved: net: hip04: fix RX buffer leak on build_skb failure When build_skb() fails in hip04_rx_poll(), the driver jumps to the refill path without releasing the current RX buffer and its DMA mapping. Installing a replacement buffer then overwrites the slot references and leaks both resources. Keep the current slot intact and return budget so NAPI retries the same buffer. Also free a newly allocated RX fragment when dma_map_single() fails. This issue was found by an in-house static analysis tool.