clk: fix a kernel-doc markup

clk_get_duty_cycle -> clk_get_scaled_duty_cycle

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/b2336f3f3cdfe6e1a2d3a7a056ab7ccc7a81b945.1603469755.git.mchehab+huawei@kernel.org


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