[arm] Cleanup dead code - old support for DImode comparisons

[arm] Cleanup dead code - old support for DImode comparisons

Now that all the major patterns for DImode have been converted to
early expansion, we can safely clean up some dead code for the old way
of handling DImode.

	* config/arm/arm-modes.def (CC_NCV, CC_CZ): Delete CC modes.
	* config/arm/arm.c (arm_select_cc_mode): Remove old selection code
	for DImode operands.
	(arm_gen_dicompare_reg): Remove unreachable expansion code.
	(maybe_get_arm_condition_code): Remove support for CC_CZmode and
	CC_NCVmode.
	* config/arm/arm.md (arm_cmpdi_insn): Delete.
	(arm_cmpdi_unsigned): Delete.

From-SVN: r277181