clk: versatile: clk-icst: Fix worthy struct documentation block

clk: versatile: clk-icst: Fix worthy struct documentation block

Also demote non-worthy header to standard comment block.

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

 drivers/clk/versatile/clk-icst.c:53: warning: Function parameter or member 'map' not described in 'clk_icst'
 drivers/clk/versatile/clk-icst.c:53: warning: Function parameter or member 'vcoreg_off' not described in 'clk_icst'
 drivers/clk/versatile/clk-icst.c:53: warning: Function parameter or member 'lockreg_off' not described in 'clk_icst'
 drivers/clk/versatile/clk-icst.c:435: warning: cannot understand function prototype: 'const struct icst_params icst525_apcp_cm_params = '

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-clk@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210120093040.1719407-20-lee.jones@linaro.org
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>