clk: zynqmp: make bestdiv unsigned

Divisor is always positive make it u32 *.
Also the arguments passed are currently of u32 pointers.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Link: https://lore.kernel.org/r/20220818113153.14431-1-shubhrajyoti.datta@amd.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>