Bring casa and casxa up to date

Bring casa and casxa up to date

src/arch/sparc/isa/decoder.isa:
    Fix up the casa and casxa instructions.
src/arch/sparc/isa/formats/formats.isa:
    This is handled in loadstore.isa now
src/arch/sparc/isa/formats/mem/basicmem.isa:
src/arch/sparc/isa/formats/mem/blockmem.isa:
    Renamed doSplitExecute to doDualSplitExecute. This differentiates between the version that does both a register and immediate version, and one that just does a register version.
src/arch/sparc/isa/formats/mem/mem.isa:
    The cas format is handled in loadstore.isa as well now.
src/arch/sparc/isa/formats/mem/util.isa:
    Reorganized things a bit to better support cas

--HG--
extra : convert_revision : 12411e89e763287e52f9825bf7a417b263c1037f