MLBEDSW-5629: MLCE: Model falling when creating explicit_padding

 - Issue was due to a previous patch to fix MLBEDSW-4350
 - Manually reverted that fix 5fabfcaa
 - Made a new fix for MLBEDSW-4350 that calculates the padding and
skirt by taking into account the split read offsets and shapes

Signed-off-by: Tim Hall <tim.hall@arm.com>
Change-Id: I96010c1b977011aecbc411a3c91ab3e61af22db4