PCI: qcom: Allow ->post_init() to fail

host_init() should detect and propagate errors from post_init().

In addition, by acknowledging that post_init() can fail we must disable the
post_init() resources in a step separate from the deinit, so that we don't
try to disable the post_init() resources a second time.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Stanimir Varbanov <svarbanov@mm-sol.com>