PCI: qcom: Fix host-init error handling

Implement the new host_deinit() callback so that the PHY is powered off
and regulators and clocks are disabled also on late host-init errors.

Fixes: 82a82383 ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>