aarch64: Add TX3 machine model

aarch64: Add TX3 machine model

Here is the patch introducing thunderx3t110 machine model
for the scheduler. A name for the new chip was added to the
list of the names to be recognized as a valid parameter for
mcpu and mtune flags. Added the TX3 tuning table and cost
model tables.

Added the new chip name to the documentation. Fixed copyright
names and dates.

Lowering the chip capabilities to v8.3 to be on the safe side.

Bootstrapped on AArch64.

2020-04-27 Anton Youdkevitch <anton.youdkevitch@bell-sw.com>

        * config/aarch64/aarch64-cores.def: Add the chip name.
        * config/aarch64/aarch64-tune.md: Regenerated.
        * config/aarch64/aarch64.c: Add tuning table for the chip.
        * gcc/config/aarch64/aarch64-cost-tables.h: Add cost tables.
        * config/aarch64/thunderx3t110.md: New file: add the new
        machine model for the scheduler
        * config/aarch64/aarch64.md: Include the new model.
        * doc/invoke.texi: Add the new name to the list