irqchip/versatile-fpga: Switch to dynamic chip name output

Move the name output to the relevant callback, which allows us
some nice cleanups (mostly owing to the fact that the driver is
now DT only.

We also drop a random include directive from the ftintc010 driver.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220209162607.1118325-8-maz@kernel.org