PCI: dwc: Use devm_pci_alloc_host_bridge() to simplify code

Use devm_pci_alloc_host_bridge() to simplify the error code path.  This
also fixes a leak in the dw_pcie_host_init() error path.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
CC: stable@vger.kernel.org	# v4.13+