ARM: Remove a (false) dependency on the memoryoperand's value as we do not use
it at the moment.
This allows to form more paired loads even when stack coloring pass destroys the
memoryoperand's value.

<rdar://problem/13978317>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184492 91177308-0d34-0410-b5e6-96231b3b80d8