[AArch64] [-mtune cleanup 3/5] [Temporary] When asked to tune for

[AArch64] [-mtune cleanup 3/5] [Temporary] When asked to tune for
 Cortex-A57, tune for Cortex-A15

gcc/
	* config/aarch64/aarch64-cores.def (cortex-a57): Tune for cortexa15.
	* config/aarch64/aarch64-tune.md: Regenerate.
	* config/aarch64/aarch64.md: Include cortex-a15 pipeline model.
	(generic_sched): "no" if we are	tuning for cortexa15.
	* config/arm/cortex-a15.md: Include cortex-a15-neon.md by
	relative path.

From-SVN: r204783