Elminate some simple_strto* usage.

checkpatch also noted pr_ conversations, which have been done as
recommended.  The pr_fmt() define is used to shorten line length.

Other multi-line string warnings are also elmininated.
Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>