epicmtd: Temporarily disable wimax.

- Temporarily remove wimax from networkAttributes.

Currently results in an NPE and system crash when calling
startMonitoring for the WIMAX tracker, which prevents the
Connectivity Service from starting.  Disable the wimax
network attribute until it's fixed.

- Set wimaxEnabled to false

Disable wimax to eliminate important, although not system killing
logcat error messages.

Change-Id: I3de591fd37a04de79cc0168b07f04af5e6db64a0