isci: Fix RNC suspend call for SCI_RESUMING state.

Instead of immediately transitioning to the SCI_RNC_AWAIT_SUSPENSION
state, handle the SCI_RNC_RESUMING suspend transition from the
SCI_RNC_READY state like the SCI_RNC_INVALIDATING --> SCI_RNC_POSTING
transitions do now, by setting the destination state for the entry
into the READY state.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>