[X86][SSE] lowerUINT_TO_FP_v2i32 - explicitly cast half word to double
[X86][SSE] lowerUINT_TO_FP_v2i32 - explicitly cast half word to double

Fixes MSVC analyzer extension->double warning.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@365027 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm