clk: zynqmp: divider: Add missing description for 'max_div'

clk: zynqmp: divider: Add missing description for 'max_div'

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

 drivers/clk/zynqmp/divider.c:46: warning: Function parameter or member 'max_div' not described in 'zynqmp_clk_divider'

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Rajan Vaja <rajan.vaja@xilinx.com>
Cc: linux-clk@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210126124540.3320214-22-lee.jones@linaro.org
Acked-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Tero Kristo <kristo@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>