[ARM][ParallelDSP] Change smlad insertion order

Instead of inserting everything after the 'root' of the reduction,
insert all instructions as close to their operands as possible. This
can help reduce register pressure.

Differential Revision: https://reviews.llvm.org/D67392

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374981 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed