net: microchip: vcap api: Always return ERR_PTR for vcap_get_rule()

As Simon Horman suggests, update vcap_get_rule() to always
return an ERR_PTR() and update the error detection conditions to
use IS_ERR(), which would be more cleaner in this case.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Suggested-by: Simon Horman <horms@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/vcap/vcap_api.c

@@ -2429,7 +2429,7 @@ struct vcap_rule *vcap_get_rule(struct vcap_control *vctrl, u32 id)
 
 	elem = vcap_get_locked_rule(vctrl, id);
 	if (!elem)
-		return NULL;
+		return ERR_PTR(-ENOENT);
 
 	rule = vcap_decode_rule(elem);
 	mutex_unlock(&elem->admin->lock);