[ARM] Deprecate -mneon-for-64bits

[ARM] Deprecate -mneon-for-64bits

Deprecate -mneon-for-64bits since it no longer has any effect after
the DImode codegen improvements.

    gcc/
	* gcc/doc/invoke.texi (mneon-for-64bits): Deprecate option.
	* gcc/config/arm/arm.opt (mneon-for-64bits): Deprecate option.
	* gcc/config/arm/arm.h (TARGET_PREFER_NEON_64BITS): Remove.
	(prefer_neon_for_64bits): Remove.
	* gcc/config/arm/arm.c (prefer_neon_for_64bits): Remove.
	(tune_params): Remove PREF_NEON_64_FALSE uses.
	(arm_option_override): Remove prefer_neon selection code.
	(arm_print_tune_info): Remove prefer_neon_for_64bits.
	* gcc/config/arm/arm-protos.h (tune_params): Remove
	prefer_neon_for_64bits.
	(prefer_neon_for_64bits): Remove.

From-SVN: r274858