Pcieutil to load the platform api first instead of using common api (s…

…onic-net#1672)

What I did
Pcieutil to load the platform api first instead of using common api
Some platform device with different BIOS version needs more than one pcie configuration to check the pcie devices properly.
Please refer to the platform api support : sonic-net/sonic-platform-common#195

How I did it
Load the platform pcie api first prior to use the common api

pcieutil/main.py

@@ -49,13 +49,18 @@ def load_platform_pcieutil():
     global platform_path
 
     # Load platform module from source
+    platform_path, _ = device_info.get_paths_to_platform_and_hwsku_dirs()
     try:
-        platform_path, _ = device_info.get_paths_to_platform_and_hwsku_dirs()
-        from sonic_platform_base.sonic_pcie.pcie_common import PcieUtil
-        platform_pcieutil = PcieUtil(platform_path)
+        from sonic_platform.pcie import Pcie
+        platform_pcieutil = Pcie(platform_path)
     except ImportError as e:
-        log.log_error("Failed to load default PcieUtil module. Error : {}".format(str(e)), True)
-        raise e
+        log.log_warning("Failed to load platform Pcie module. Error : {}, fallback to load Pcie common utility.".format(str(e)), True)
+        try:
+            from sonic_platform_base.sonic_pcie.pcie_common import PcieUtil
+            platform_pcieutil = PcieUtil(platform_path)
+        except ImportError as e:
+            log.log_error("Failed to load default PcieUtil module. Error : {}".format(str(e)), True)
+            raise e
 
 
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