[MIPS][lldb-server] Add 32-bit register context and read/write FP registers on mips64

    - Added support for read/write FP registers in FR1 mode.
    - Added 32 bit register context for mips32.

Reviewers: clayborg, tberghammer, jaydeep
Subscribers: emaste, nitesh.jain, bhushan, mohit.bhakkad, lldb-commits
Differential Revision: http://reviews.llvm.org/D10029

llvm-svn: 238914