drm/radeon/dpm/btc: filter clocks based on voltage/clk dep tables

Filter out mclk and sclk levels higher than listed in the clk
voltage dependency tables.  Supporting these clocks will require
additional driver tweaking that isn't supported yet.

See bug:
https://bugs.freedesktop.org/show_bug.cgi?id=68235



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>