clk: mvebu: ap-cpu-clk: Demote non-conformant kernel-doc header

clk: mvebu: ap-cpu-clk: Demote non-conformant kernel-doc header

Not much effort has been put into this one.

Demote it for the time being at least.

Fixes the following W=1 kernel build warning(s):

 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'ratio_state_reg' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'divider_mask' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'cluster_offset' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'force_mask' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'divider_offset' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'divider_ratio' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'ratio_offset' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'ratio_state_offset' not described in 'cpu_dfs_regs'
 drivers/clk/mvebu/ap-cpu-clk.c:52: warning: Function parameter or member 'ratio_state_cluster_offset' not described in 'cpu_dfs_regs'

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Julia Lawall <Julia.Lawall@inria.fr>
Cc: Omri Itach <omrii@marvell.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: linux-clk@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210120093040.1719407-10-lee.jones@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>