clk: sifive: sifive-prci: convert from round_rate() to determine_rate()

clk: sifive: sifive-prci: 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 the changes to the three header files were done by hand.

Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Signed-off-by: Brian Masney <bmasney@redhat.com>