PCI: xgene: Revert "PCI: xgene: Fix IB window setup"

Commit c7a75d0782 ("PCI: xgene: Fix IB window setup") tried to
fix the damages that 6dce5aa59e ("PCI: xgene: Use inbound resources
for setup") caused, but actually didn't improve anything for some
plarforms (at least Mustang and m400 are still broken).

Given that 6dce5aa59e has been reverted, revert this patch as well,
restoring the PCIe support on XGene to its pre-5.5, working state.

Link: https://lore.kernel.org/r/YjN8pT5e6/8cRohQ@xps13.dannf
Link: https://lore.kernel.org/r/20220321104843.949645-3-maz@kernel.org
Fixes: c7a75d0782 ("PCI: xgene: Fix IB window setup")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: stable@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: Toan Le <toan@os.amperecomputing.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Krzysztof Wilczyński <kw@linux.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Stéphane Graber <stgraber@ubuntu.com>
Cc: dann frazier <dann.frazier@canonical.com>

drivers/pci/controller/pci-xgene.c

@@ -465,7 +465,7 @@ static int xgene_pcie_select_ib_reg(u8 *ib_reg_mask, u64 size)
 		return 1;
 	}
 
-	if ((size > SZ_1K) && (size < SZ_4G) && !(*ib_reg_mask & (1 << 0))) {
+	if ((size > SZ_1K) && (size < SZ_1T) && !(*ib_reg_mask & (1 << 0))) {
 		*ib_reg_mask |= (1 << 0);
 		return 0;
 	}