CP-6335: Removal of dm-multipath-init patch

This functionality has stopped being a patch to upstream
multipath and it is shipped in its own startup script
provided by sm RPM

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Vineeth Thampi Raveendran <vineeth.thampi@citrix.com>

GitHub: closes #42 on xapi-project/sm