staging: mt29f: clean up existing kernel-doc

The existing kerneldoc blocs had a few issues:
- some of them didn't start with /**
- some used -- instead of - to separate the short description
- some descriptions had text looking like section headers
- some descriptions started with "to" while some used the imperative: use the
  imperative everywhere
- some had a "with:" at the end of the shortdesc that didn't make sense once
  formatted by kernel-docs
- two argument names where out of sync with the prototype

Signed-off-by: Manuel Pégourié-Gonnard <mpg@elzevir.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>