Don't hard code the function names in the diagnostic output when these
reset related routines fail. Instead, use %s and __func__ so that future
refactors don't need to change the print outs.

Additionally, while we are here, add missing function header comments
for the new reset_prepare and reset_done function handlers.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>