clk: clk-fixed-mmio: Demote obvious kernel-doc abuse

clk: clk-fixed-mmio: Demote obvious kernel-doc abuse

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

 drivers/clk/clk-fixed-mmio.c:62: warning: Function parameter or member 'pdev' not described in 'of_fixed_mmio_clk_probe'

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jan Kotas <jank@cadence.com>
Cc: linux-clk@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210126124540.3320214-15-lee.jones@linaro.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>