iwlwifi: remove ucode error tracepoint

Alexei's patch, assumed that all versions of "struct iwl_error_event_table"
are the same, but there are really different versions in different files.

Rather than trying to fix this, or splitting the tracepoint, or anything of
the sort, just remove it entirely - turns out that nobody really uses it.

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