clk: bcm: rpi: Make sure pllb_arm is removed

clk: bcm: rpi: Make sure pllb_arm is removed

The pllb_arm clock was created at probe time, but was never removed if
something went wrong later in probe, or if the driver was ever removed from
the system.

Now that we are using clk_hw_register, we can just use its managed variant
to take care of that for us.

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>