clk: vc3: Fix 64 by 64 division

Fix the below cocci warnings by replacing do_div()->div64_ul() and
bound the result with a max value of U16_MAX.

cocci warnings:
	drivers/clk/clk-versaclock3.c:404:2-8: WARNING: do_div() does a
	64-by-32 division, please consider using div64_ul instead.

Reported-by: Julia Lawall <julia.lawall@inria.fr>
Closes: https://lore.kernel.org/r/202307270841.yr5HxYIl-lkp@intel.com/
Fixes: 6e9aff55

 ("clk: Add support for versa3 clock driver")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230824104812.147775-3-biju.das.jz@bp.renesas.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>