[fix] wrong function pointers in layout_pad_row

The new padded tilings uncovered bugs in the operator table and the
implementation of padded layouts in row-major. We've seen these issues
before, we should be a bit more careful in the future.
5 jobs for tilings-pad in 11 minutes and 4 seconds (queued for 1 second)
Status Job ID Name Coverage
  Style
passed #45908
integration
checkpatch

00:01:40

passed #45907
integration
repoquality

00:05:23

 
  Build
passed #45909
make:generic

00:01:36

passed #45911
knl
make:knl

00:02:28

passed #45910
make:out-of-tree

00:01:36