clocksource: Augment bindings for Faraday timer

It turns out that the Cortina Gemini timer block is just a
standard IP block from Faraday Technology named FTTMR010.

In order to make things clear and understandable, we rename the
bindings with a Faraday compatible as primary and the Cortina
gemini as a more specific case.

For the plain Faraday timer we require two clock references,
while the Gemini can keep it's syscon lookup pattern.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>