x86/mmiotrace: Remove redundant instruction prefix checks

Get rid of the duplicated entries in prefix_codes[]
to eliminate redundant checks by skip_prefix().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Pekka Paalanen <pq@iki.fi>
LKML-Reference: <1274140110-5841-1-git-send-email-akinobu.mita@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>