Impact: cleanup, solve 80 columns wrap problems

It would be cleaner to rename all the mpf->mpf_X fields to
mpf->X - that alone would give 4 characters per usage site.
(we already know that it's an 'mpf' entity -
no need to duplicate that in the field too)
Signed-off-by: NJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>