This patch adds support for Arm's Neoverse N2 CPU to AArch64 binutils.

Testing:
 * Regression tested on aarch64-none-elf.

OK for master?

Thanks,
Alex

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gas/ChangeLog:

2020-09-23  Alex Coplan  <alex.coplan@arm.com>

	* config/tc-aarch64.c (aarch64_cpus): Add neoverse-n2.
	* doc/c-aarch64.texi: Document support for Neoverse N2.