Update omci-lib-go to 2.2.0 and use new ME attribute constants instead of strings

Change-Id: If0bee47bede5e02c70f73c6c615bafc55d1389d5
diff --git a/go.sum b/go.sum
index 4c127d9..4ce0602 100644
--- a/go.sum
+++ b/go.sum
@@ -87,8 +87,8 @@
 github.com/opencord/cordctl v0.0.0-20190909161711-01e9c1f04bf4/go.mod h1:/+3S0pwQUy7HeKnH0KfKp5W6hmh/LdZzuZTNT/m7vA4=
 github.com/opencord/device-management-interface v1.2.1 h1:ur7l70Le6Xzemb7Y/2wkO7u9jA26bLnB4R0+5SIoy+I=
 github.com/opencord/device-management-interface v1.2.1/go.mod h1:G1owSqGBGaqllrwtjxfLTsy9EDsGhdhmqkJM3XOnPD0=
-github.com/opencord/omci-lib-go/v2 v2.1.2 h1:IgwSGEtM8zf/o8wrDLdY+q0WshDYwRwMGYeL35gMqVQ=
-github.com/opencord/omci-lib-go/v2 v2.1.2/go.mod h1:o1S/jhDLHNikFU7uG2TR5UOM5KmKlqwLlVncXi0FBYQ=
+github.com/opencord/omci-lib-go/v2 v2.2.0 h1:9eawwD1+oWHTzEv9Q/JeSN12N/3YSGKoj1dr2Pm434g=
+github.com/opencord/omci-lib-go/v2 v2.2.0/go.mod h1:o1S/jhDLHNikFU7uG2TR5UOM5KmKlqwLlVncXi0FBYQ=
 github.com/opencord/voltha-protos/v5 v5.1.2 h1:biyhoK+5JBcpT3HvUBb1xzN5cAKA0xXU/hLbtzuR9xI=
 github.com/opencord/voltha-protos/v5 v5.1.2/go.mod h1:dvz08S+JLdfjhFtd3Rf38DLeD9jQ6JO1+0K3NTdheRo=
 github.com/pierrec/lz4 v2.4.1+incompatible h1:mFe7ttWaflA46Mhqh+jUfjp2qTbPYxLB2/OyBppH9dg=