clk: <linux/clk-provider.h>: drop a duplicated word

Drop the repeated word "not" in a comment.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Link: https://lore.kernel.org/r/20200719002830.20319-1-rdunlap@infradead.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>