PCI: cadence: Allow PTM Responder to be enabled

This enables the Controller [RP] to automatically respond with
Response/ResponseD messages if CDNS_PCIE_LM_TPM_CTRL_PTMRSEN
and PCI_PTM_CTRL_ENABLE bits are both set.

Link: https://lore.kernel.org/r/20220512055539.1782437-1-christian.gmeiner@gmail.com


Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>