drm/panthor: return error on truncated firmware

panthor_fw_load() detects truncated firmware images, but jumps to the
common cleanup path without setting ret. If no previous error was recorded,
the function can return 0 and treat the invalid firmware as successfully
loaded.

Set ret to -EINVAL before leaving the truncated-image path.

Fixes: 2718d91 ("drm/panthor: Add the FW logical block")
Cc: stable@vger.kernel.org
Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patch.msgid.link/20260714163056.22329-1-osama.abdelkader@gmail.com
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

Author: osamakader

drivers/gpu/drm/panthor/panthor_fw.c

@@ -829,6 +829,7 @@ static int panthor_fw_load(struct panthor_device *ptdev)
 	}
 
 	if (hdr.size > iter.size) {
+		ret = -EINVAL;
 		drm_err(&ptdev->base, "Firmware image is truncated\n");
 		goto out;
 	}