R600: remove nonsense setPrefLoopAlignment

The Align parameter is a power of two, so 16 results in 64K
alignment. Additional to that even 16 byte alignment doesn't
make any sense, so just remove it.

Patch by: Christian König

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Christian König <deathsimple@vodafone.de>
llvm-svn: 170341