PCI: cadence: Fix runtime atomic count underflow

If the call to pci_host_probe() in cdns_pcie_host_setup() fails, PM
runtime count is decremented in the error path using pm_runtime_put_sync().
But the runtime count is not incremented by this driver, but only by the
callers (cdns_plat_pcie_probe/j721e_pcie_probe). And the callers also
decrement the runtime PM count in their error path. So this leads to the
below warning from the PM core:

	"runtime PM usage count underflow!"

So fix it by getting rid of pm_runtime_put_sync() in the error path and
directly return the errno.

Fixes: 49e427e6 ("Merge branch 'pci/host-probe-refactor'")
Signed-off-by: Hans Zhang <18255117159@163.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250419133058.162048-1-18255117159@163.com