clocksource/drivers/fttmr010: Merge Moxa into FTTMR010

This merges the Moxa Art timer driver into the Faraday FTTMR010
driver and replaces all Kconfig symbols to use the Faraday
driver instead. We are now so similar that the drivers can
be merged by just adding a few lines to the Faraday timer.

Differences:

- The Faraday driver explicitly sets the counter to count
  upwards for the clocksource, removing the need for the
  clocksource core to invert the value.

- The Faraday driver also handles sched_clock()

On the Aspeed, the counter can only count downwards, so support
the timers in downward-counting mode as well, and flag the
Aspeed to use this mode. This mode was tested on the Gemini so
I have high hopes that it'll work fine on the Aspeed as well.

After this we have one driver for all three SoCs and a generic
Faraday FTTMR010 timer driver, which is nice.

Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>