drm/amd/display: re-indent dc_power_down_on_boot()

These lines are indented too far.  Clean the whitespace.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>