[tilegx] Delete useless target ISD opcode.

  CMovFP_T, CMovFP_F are copied from mips.
[tilegx] Native support for cmpXXX.

  previously, some of them are supported by indirect way, for example,

  cmpne converted to "xor c, a, b + cmpltu c, zero, c", as our hardware
  support "cmpne" directly, we should remove such conversions.
[tilegx] fix one opcode bug & cleanup redundant instruction matching patterns.