Condense the first two arguments of the linear solver so that we don't need to make a copy

[K20shores]

The first and second argument of the linear solver are the same and we always have to make a copy. In #485 the forcing vector was just passed in for both arguments and things worked. That means we can remove one of the arguments and prevent a copy.

Acceptance

• There is only one matrix passed into linear solve
• The copy of the matrix is removed from the CPU and GPU versions of Rosenbrock