[barefoot][platform] platform API 2.0 fixes (#6607)

To improve python3 support of berefoot's sonic_platform

Signed-off-by: Volodymyr Boyko <volodymyrx.boiko@intel.com>

platform/barefoot/sonic-platform-modules-bfn-montara/sonic_platform/eeprom.py

@@ -17,7 +17,7 @@
     from sonic_eeprom import eeprom_base
     from sonic_eeprom import eeprom_tlvinfo
 
-    from .platform_thrift_client import thrift_try
+    from platform_thrift_client import thrift_try
 except ImportError as e:
     raise ImportError (str(e) + "- required module not found")
 
@@ -64,6 +64,11 @@
 EEPROM_SYMLINK = "/var/run/platform/eeprom/syseeprom"
 EEPROM_STATUS = "/var/run/platform/eeprom/status"
 
+try:
+    _str_type = basestring
+except NameError:
+    _str_type = str
+
 class Eeprom(eeprom_tlvinfo.TlvInfoDecoder):
     def __init__(self):
 
@@ -101,15 +106,15 @@ def eeprom_parse(self):
         f.close()
 
         eeprom_params = ""
-        for attr, val in self.eeprom.__dict__.iteritems():
+        for attr, val in self.eeprom.__dict__.items():
             if val is None:
                 continue
 
             elem = eeprom_default_dict.get(attr)
             if elem is None:
                 continue
 
-            if isinstance(val, basestring):
+            if isinstance(val, _str_type):
                 value = val.replace('\0', '')
             else:
                 value = str(val)