[arm] Add support for Neoverse N1

[arm] Add support for Neoverse N1

This patch adds support for the Neoverse N1 [1]. This CPU was previously supported through the Ares codename.
-mcpu=ares is retained as an alias of the new -mcpu=neoverse-n1.

Bootstrapped and tested on arm-none-linux-gnueabihf.

	* config/arm/arm-cpus.in (ares): Rename to...
	(neoverse-n1): ... This.  Add ares as alias.
	* config/arm/arm-tables.opt: Regenerate.
	* config/arm/arm-tune.md: Likewise.
	* doc/invoke.txt (ARM Options): Document neoverse-n1.

From-SVN: r269101