clk: hisilicon: Remove unnecessary local variable

clk: hisilicon: Remove unnecessary local variable

The local u64 variable refdiv_val has the same value as the local u32
variable val and can be removed. Remove it and use val directly as the
divisor to also remove the following Coccinelle/coccicheck warning
reported by do_div.cocci:

  WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead

Use the preferred div_u64() function instead of the do_div() macro.

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Link: https://lore.kernel.org/r/20240801103616.20430-1-thorsten.blum@toblux.com
Acked-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>