iwlwifi: remove uCode alternatives mechanism

We've never released firmware using the alternatives
mechanism and our build process makes that difficult
anyway. This means that in every file we have ever
built (except maybe by hand for testing) the listed
alternative was 0. Make the alternative field in the
TLVs part of the TLV number (thus expanding that to
32 bits); this gives us more TLV numbers (not really
needed) and more importantly protects against rogue
firmware files that actually do use the alternatives
mechanism -- those will now be rejected since they
don't contain any valid TLVs.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>