drm/amd/display: Fix timer_per_pixel unit error

[why]
The units of the time_per_pixel variable were incorrect, this had to be
changed for the code to properly function.

[how]
The change was very straightforward, only required one line of code to
be changed where the calculation was done.

Acked-by: Rodrigo Siqueira <[e-mail]>
Signed-off-by: Oliver Logush <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c

···
 				wb_arb_params->cli_watermark[k] = get_wm_writeback_urgent(&context->bw_ctx.dml, pipes, pipe_cnt) * 1000;
 				wb_arb_params->pstate_watermark[k] = get_wm_writeback_dram_clock_change(&context->bw_ctx.dml, pipes, pipe_cnt) * 1000;
 			}
-			wb_arb_params->time_per_pixel = 16.0 / context->res_ctx.pipe_ctx[i].stream->phy_pix_clk; /* 4 bit fraction, ms */
+			wb_arb_params->time_per_pixel = 16.0 * 1000 / (context->res_ctx.pipe_ctx[i].stream->phy_pix_clk / 1000); /* 4 bit fraction, ms */
 			wb_arb_params->slice_lines = 32;
 			wb_arb_params->arbitration_slice = 2;
 			wb_arb_params->max_scaled_time = dcn20_calc_max_scaled_time(wb_arb_params->time_per_pixel,