[DellEMC] Fix Z9100 port index issue (#4309)

platform/broadcom/sonic-platform-modules-dell/z9100/sonic_platform/chassis.py

@@ -163,6 +163,28 @@ class Chassis(ChassisBase):
         """
         return self._eeprom.serial_str()
     
+    def get_sfp(self, index):
+        """
+        Retrieves sfp represented by (1-based) index <index>
+
+        Args:
+            index: An integer, the index (1-based) of the sfp to retrieve.
+                   The index should be the sequence of a physical port in a chassis,
+                   starting from 1.
+                   For example, 0 for Ethernet0, 1 for Ethernet4 and so on.
+
+        Returns:
+            An object dervied from SfpBase representing the specified sfp
+        """
+        sfp = None
+
+        try:
+            sfp = self._sfp_list[index-1]
+        except IndexError:
+            sys.stderr.write("SFP index {} out of range (1-{})\n".format(
+                             index, len(self._sfp_list)-1))
+        return sfp
+
     def get_status(self):
         """
         Retrieves the operational status of the chassis