Previously, each freed cluster was unmapped individually.
Instead, coalesce unmaps for contiguous clusters to reduce
the volume of commands sent.
Change-Id: I6ea1d2e1235e3c030cd2826c97e57aca571bd2ae
Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/362773
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>