powerplay: Respect units on max dcfclk watermark

In a refactor, the watermark clock inputs to
powerplay from DC were changed from units of 10kHz to
kHz clocks.

One division by 100 was not converted into a division
by 1000.

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>