Revert "[DebugInfo] Emit DW_OP_implicit_value for Floating point constants"

This reverts commit 6b55a958.
Temporal revert due to a failing/assertion in test case in Sparc backend.
`test/DebugInfo/Sparc/subreg.ll`
Seen in lot of bots, for instance in:
`http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/24679`