clk: renesas: Pass clock rate around as 64bit number internally

clk: renesas: Pass clock rate around as 64bit number internally

The PLL rate could be in the GHz range, which could overflow a 32bit
data type. Since the hardware is 64bit anyway, pass the clock rates
as 64bit number internally to avoid this.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>