clk: socfpga: remove redundant assignment on division

The variable parent_rate is being divided by div and the result
is re-assigned to parent_rate before being returned. The assignment
is redundant, replace /= operator with just / operator.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20211221003750.212780-1-colin.i.king@gmail.com


Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>