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.

Fixes: 1241c56 ("wifi: wilc1000: Fill in missing error handling")
Signed-off-by: Shitalkumar Gandhi <shitalkumar.gandhi@cambiumnetworks.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260511042732.998311-1-shitalkumar.gandhi@cambiumnetworks.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Author: Shitalkumar Gandhi

drivers/net/wireless/microchip/wilc1000/wlan.c

@@ -1265,7 +1265,7 @@ int wilc_wlan_firmware_download(struct wilc *wilc, const u8 *buffer,
 
 	ret = acquire_bus(wilc, WILC_BUS_ACQUIRE_AND_WAKEUP);
 	if (ret)
-		return ret;
+		goto fail;
 
 	wilc->hif_func->hif_read_reg(wilc, WILC_GLB_RESET_0, &reg);
 	reg &= ~BIT(10);