FROMLIST: PCI: qcom: Add .get_ltssm() helper

[krishnachaitanya-linux]

For older targets like sc7280, we see reading DBI after sending PME turn off message is causing NOC error.

To avoid unsafe DBI accesses, introduce qcom_pcie_get_ltssm(), which retrieves the LTSSM state from the PARF_LTSSM register instead.

Link: https://lore.kernel.org/r/20260217-d3cold-v2-3-89b322864043@oss.qualcomm.com

CRs-Fixed: 4440925

[qcomlnxci]

Test jobs on e39cedc

• Job 41172 on kaanapali-mtp
• Job 41203 on lemans-evk
• Job 41169 on monaco-evk
• Job 41173 on qcs615-ride
• Job 41170 on qcs6490-rb3gen2
• Job 41171 on qcs8300-ride
• Job 41285 on qcs9100-ride-r3
• Job 41168 on sm8750-mtp
• Job 41167 on x1e80100-crd

[qcomlnxci]

Test Matrix

Test Case	kaanapali-mtp	lemans-evk	monaco-evk	qcs615-ride	qcs6490-rb3gen2	qcs8300-ride	qcs9100-ride-r3	sm8750-mtp	x1e80100-crd
0_qcom-next-ci-premerge-tests	◻️	❌ Fail	❌ Fail	◻️	❌ Fail	❌ Fail	❌ Fail	❌ Fail	◻️
BT_FW_KMD_Service	◻️	❌ Fail	❌ Fail	◻️	✅ Pass	❌ Fail	✅ Pass	❌ Fail	◻️
BT_ON_OFF	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	⚠️ skip	◻️
BT_SCAN	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	⚠️ skip	◻️
CPUFreq_Validation	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
CPU_affinity	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
DSP_AudioPD	◻️	❌ Fail	✅ Pass	◻️	✅ Pass	✅ Pass	❌ Fail	◻️	◻️
Ethernet	◻️	⚠️ skip	⚠️ skip	◻️	⚠️ skip	⚠️ skip	⚠️ skip	⚠️ skip	◻️
Freq_Scaling	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
GIC	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
IPA	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
Interrupts	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
OpenCV	◻️	⚠️ skip	⚠️ skip	◻️	⚠️ skip	⚠️ skip	⚠️ skip	◻️	◻️
PCIe	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
Probe_Failure_Check	◻️	❌ Fail	❌ Fail	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
RMNET	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
UFS_Validation	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
USBHost	◻️	❌ Fail	❌ Fail	◻️	❌ Fail	✅ Pass	✅ Pass	❌ Fail	◻️
WiFi_Firmware_Driver	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	◻️	◻️
WiFi_OnOff	◻️	⚠️ skip	⚠️ skip	◻️	✅ Pass	✅ Pass	✅ Pass	◻️	◻️
cdsp_remoteproc	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	❌ Fail	◻️
hotplug	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
irq	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
kaslr	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
pinctrl	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
qcom_hwrng	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	◻️	◻️
remoteproc	◻️	✅ Pass	❌ Fail	◻️	✅ Pass	❌ Fail	✅ Pass	❌ Fail	◻️
rngtest	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	❌ Fail	✅ Pass	✅ Pass	◻️
shmbridge	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	❌ Fail	✅ Pass	✅ Pass	◻️
smmu	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️
watchdog	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	◻️	◻️
wpss_remoteproc	◻️	✅ Pass	✅ Pass	◻️	✅ Pass	✅ Pass	✅ Pass	✅ Pass	◻️