PCI: apple: Initialize pcie->nvecs before use

The apple_pcie_setup_port() function computes ilog2(pcie->nvecs) to set
up the number of MSIs available for each port. However, it's called
before apple_msi_init(), which initializes pcie->nvecs.

Luckily, pcie->nvecs is part of kzalloc()-ed structure and, as such,
initialized as zero. ilog2(0) happens to be 0xffffffff which then simply
configures more MSIs in hardware than we have. This doesn't break
anything because we never hand out those vectors.

Thus, swap the order of the two calls so that the correctly initialized
value is then used.

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20230311133453.63246-1-sven@svenpeter.dev
Fixes: 476c41e ("PCI: apple: Implement MSI support")
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>

Author: svenpeter42

drivers/pci/controller/pcie-apple.c

@@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 	cfg->priv = pcie;
 	INIT_LIST_HEAD(&pcie->ports);
 
+	ret = apple_msi_init(pcie);
+	if (ret)
+		return ret;
+
 	for_each_child_of_node(dev->of_node, of_port) {
 		ret = apple_pcie_setup_port(pcie, of_port);
 		if (ret) {
@@ -792,7 +796,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 		}
 	}
 
-	return apple_msi_init(pcie);
+	return 0;
 }
 
 static int apple_pcie_probe(struct platform_device *pdev)