Qualcomm PCIe controllers have debug registers in the MMIO region
that count PCIe link transitions. Expose them over debugfs to
userspace to help debug the low power issues.

Link: https://lore.kernel.org/r/20220914075350.7992-6-manivannan.sadhasivam@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: NLorenzo Pieralisi <lpieralisi@kernel.org>