Minor grammar and word usage fix to 'returned' parameter attribute section of LangRef
R600: Expand v2i32 load/store instead of custom lowering

The custom lowering causes llc to crash with a segfault.

Ideally, the custom lowering can be fixed, but this allows
programs which load/store v2i32 to work without crashing.

Patch by: Aaron Watry

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Aaron Watry<awatry@gmail.com>
R600/SI: Expand add for v2i32 and v4i32

Also add SI tests to existing file and a v2i32 test for both
R600 and SI.

Patch by: Aaron Watry

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Aaron Watry <awatry@gmail.com>
R600/SI: Expand sub for v2i32 and v4i32 for SI

Also add a v2i32 test to the existing v4i32 test.

Patch by: Aaron Watry

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Aaron Watry<awatry@gmail.com>