R600/SI: Change formatting of printed FP immediates

Only 1 decimal place should be printed for inline immediates.
Other constants should be hex constants.

Does not include f64 tests because folding those inline
immediates currently does not work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217964 91177308-0d34-0410-b5e6-96231b3b80d8