um: vector: fix bpfflash parameter evaluation

With W=1 the build complains about a pointer compared to
zero, clearly the result should've been compared.

Fixes: 9807019a ("um: Loadable BPF "Firmware" for vector drivers")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Tiwei Bie <tiwei.btw@antgroup.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/drivers/vector_kern.c

@@ -141,7 +141,7 @@ static bool get_bpf_flash(struct arglist *def)
 
 	if (allow != NULL) {
 		if (kstrtoul(allow, 10, &result) == 0)
-			return (allow > 0);
+			return result > 0;
 	}
 	return false;
 }