work-around what appears to be a pylint bug

smpp.pdu.pdu_types.DataCodingScheme.GSM_MESSAGE_CLASS very much exists,
and I can prove that manually in the python shell.  So let's assume this
is a pylint bug and work around it

pySim/sms.py:72:21: E1101: Instance of 'DataCodingScheme' has no 'GSM_MESSAGE_CLASS' member (no-member)

Change-Id: Iab34bae06940fecf681af9f45b8657e9be8cbc7b
---
M pySim/sms.py
1 file changed, 17 insertions(+), 0 deletions(-)

diff --git a/pySim/sms.py b/pySim/sms.py
index a15bbcb..88ee27a 100644
--- a/pySim/sms.py
+++ b/pySim/sms.py
@@ -69,6 +69,8 @@
     if dcs == pdu_types.DataCoding(pdu_types.DataCodingScheme.DEFAULT,
                                    pdu_types.DataCodingDefault.OCTET_UNSPECIFIED_COMMON):
         return True
+    # pySim/sms.py:72:21: E1101: Instance of 'DataCodingScheme' has no 'GSM_MESSAGE_CLASS' member (no-member)
+    # pylint: disable=no-member
     if dcs.scheme == pdu_types.DataCodingScheme.GSM_MESSAGE_CLASS and dcs.schemeData['msgCoding'] == pdu_types.DataCodingGsmMsgCoding.DATA_8BIT:
         return True
     else:

