clk: bcm: rpi: Remove pllb_arm_lookup global pointer

clk: bcm: rpi: Remove pllb_arm_lookup global pointer

The pllb_arm_lookup pointer in the struct raspberrypi_clk is not used for
anything but to store the returned pointer to clkdev_hw_create, and is not
used anywhere else in the driver.

Let's remove that global pointer from the structure.

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>
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/189407f54906d2b07c91de7a4eeb6d8c8934280f.1592210452.git-series.maxime@cerno.tech
Signed-off-by: Stephen Boyd <sboyd@kernel.org>