iwlwifi: unify external & internal modparam names

Where possible (all except for "11n_disable", which isn't valid in C)
rename the internal names for module parameters to be the same as the
externally visible names, to aid finding their use etc.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>