PCI: dwc: Fix setting error return on MSI DMA mapping failure

PCI: dwc: Fix setting error return on MSI DMA mapping failure

When dma_mapping_error() returns error because of no enough memory,
but dw_pcie_host_init() returns success, which will mislead the callers.

Link: https://lore.kernel.org/r/30170911-0e2f-98ce-9266-70465b9073e5@huawei.com
Fixes: 07940c369a6b ("PCI: dwc: Fix MSI page leakage in suspend/resume")
Signed-off-by: Jianrong Zhang <zhangjianrong5@huawei.com>
Signed-off-by: Jiantao Zhang <water.zhangjiantao@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>