clk: bcm: rpi: Add clock id to data

clk: bcm: rpi: Add clock id to data

The driver has really only supported one clock so far and has hardcoded the
ID used in communications with the firmware in all the functions
implementing the clock framework hooks. Let's store that in the clock data
structure so that we can support more clocks later on.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: linux-clk@vger.kernel.org
Acked-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>