staging/rdma/hfi1: fix sdma build failures to always clean up

There are holes in the sdma build support routines that do
not clean any partially built sdma descriptors after mapping or
allocate failures.

This patch corrects these issues.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>