wifi: rtw89: pci: enable LTR based on pcie control register

wifi: rtw89: pci: enable LTR based on pcie control register

Originally, driver always transmits LTR (Latency Tolerance Reporting) to
pcie host, but it may cause pcie link down on some platforms because
LTR is not supported. As a result, driver will check the control
register of LTR setting to decide whether to enable LTR feature.

This applies to Wi-Fi 6 chips only. For Wi-Fi 7 chips, although the
driver still issues LTR, the hardware has its own internal logic
to determine whether to actually transmit it to pcie host.

Signed-off-by: Dian-Syuan Yang <dian_syuan0116@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20260515014433.16168-5-pkshih@realtek.com