aarch64: add support for Cortex-A78 and Cortex-A78AE

aarch64: add support for Cortex-A78 and Cortex-A78AE

This patch introduces support for Cortex-A78 [0] and Cortex-A78AE [1]
cpus.

    [0]: https://www.arm.com/products/silicon-ip-cpu/cortex-a/cortex-a78
    [1]: https://www.arm.com/products/silicon-ip-cpu/cortex-a/cortex-a78ae

OK for master branch ?

kind regards
Przemyslaw Wirkus

gcc/ChangeLog:

	* config/aarch64/aarch64-cores.def: Add Cortex-A78 and Cortex-A78AE cores.
	* config/aarch64/aarch64-tune.md: Regenerate.
	* doc/invoke.texi: Add -mtune=cortex-a78 and -mtune=cortex-a78ae.