[SPARC] Repair floating-point condition encodings in assembly parser.

The encodings for floating point conditions A(lways) and N(ever) were
incorrectly specified for the assembly parser, per Sparc manual v8 page
121. This change corrects that mistake.

Also, strangely, all of the branch instructions already had MC test
cases, except for the broken ones. Added the tests.

Patch by Chris Dewhurst

Differential Revision: http://reviews.llvm.org/D17074

llvm-svn: 260390