clk: scmi: Fix the rounding of clock rate

This fix rounds the clock rate properly by using quotient and not
remainder in the calculation. This issue was found while testing HDMI
in the Juno platform.

Fixes: 6d6a1d82 ("clk: add support for clocks provided by SCMI")
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>