Changes

Omit all-zero octets in MS Classmark 3

TS 24.008 Clause 10.5.7.1 allows us to omit all-zero octets at the end
of the information element. The decoder will add them if needed.

Older specs tell us to include the supported bands, a5 bits and radio
capability. Therefore we don't omit them, even if their encoded octets
are all-zero.

Change-Id: I3f05893e60f37f349b77fbd15a20b7708c4c3481