gpio: Add gpio driver support for ThunderX and OCTEON-TX

Cavium ThunderX and OCTEON-TX are arm64 based SoCs.  Add driver for
the on-chip GPIO pins.

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
3 files changed