Make EnableFailFastRefCounter a singleton.

Since there is only one DCT the mEnableFailFastRefCounter can be a
static/singleton and thus properly refcount the
CMD_SET_ENABLE_FAIL_FAST_MOBILE_DATA. There is still one problem
and that is if the PhoneApp crashes the singleton will be reinstantiated
and we'll have the same problem, but the frequency of this is small.
Also, the consequence of this is the DCT will be behaving "normally"
in that it will be attempting to do data-stall recovery although we
might like it not to it is the "normal" behavior.

Bug: 10304904
Change-Id: I38ff37445788ec952ca26be45b0374bc0a7ae34d