iwlwifi: fw: move assert descriptor parser to common code

Move this parser to a common place, instead of having it in code that
is specific to mvm.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200911204056.45b270b0bf2f.I4561138cd5be9f44fa42cfce10258de0607be40f@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>