wifi: wilc1000: fix dma_buffer leak on bus acquire failure

In the Linux kernel, the following vulnerability has been resolved: wifi: wilc1000: fix dma_buffer leak on bus acquire failure wilc_wlan_firmware_download() allocates dma_buffer with kmalloc() at the top of the function and uses a 'fail:' label to free it via kfree(dma_buffer) on error. All later error paths correctly use 'goto fail' to route through this cleanup. However, the early failure path after the first acquire_bus() call uses a bare 'return ret;', which leaks dma_buffer whenever the bus acquire fails. Replace the early return with goto fail so the existing cleanup path runs. Found via a custom Coccinelle semantic patch hunting for kmalloc'd locals leaked on early-return error paths in driver firmware-download code.