clk: st: clkgen-pll: convert from round_rate() to determine_rate()

clk: st: clkgen-pll: convert from round_rate() to determine_rate()

The round_rate() clk ops is deprecated, so migrate this driver from
round_rate() to determine_rate() using the Coccinelle semantic patch
on the cover letter of this series.

Note that prior to running the Coccinelle:

- round_rate_stm_pll4600c28() was renamed to stm_pll4600c28_round_rate()
- round_rate_stm_pll3200c32() was renamed to stm_pll3200c32_round_rate()

Signed-off-by: Brian Masney <bmasney@redhat.com>