clk: Remove a useless include

<linux/rational.h> is not needed for these drivers. Remove the
corresponding #include.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/12dd5cb49efa7714f8e0389e4c7b3bc829e8a90e.1668289299.git.christophe.jaillet@wanadoo.fr


Acked-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>