Re-work the msi_msg DMA allocation logic to use dmam_alloc_coherent() which
uses the coherent DMA mask to try to return an allocation within the DMA
mask limits. With that, we now can drop the msi_page parameter in struct
dw_pcie_rp. This allows kernel configurations that disable ZONE_DMA32 to
continue supporting a 32-bit DMA mask. Without this patch, the PCIe host
device will fail to probe when ZONE_DMA32 is disabled.

Link: https://lore.kernel.org/r/20220825235404.4132818-2-willmcvicker@google.com
Fixes: 35797e67 ("PCI: dwc: Fix MSI msi_msg DMA mapping")
Reported-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Signed-off-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>