LSR: Fix the parameters used to compute the scaling factor cost.

Prior to this change, the considered addressing modes may be invalid since the
maximum and minimum offsets were not taking into account.
This was causing an assertion failure.

The added test case exercices that behavior.

<rdar://problem/14199725> Assertion failed: (CurScaleCost >= 0 && "Legal
addressing mode has an illegal cost!")

llvm-svn: 184341