drm/amd/powerply: fix power reading on Fiji

Power value is wrong reported by customer. It is a regression by

commit a7c7bc4c0c47eaac77b8fa92f0672032df7f4254
Author: Rex Zhu <Rex.Zhu@amd.com>
Date:   Mon Mar 27 15:32:59 2017 +0800

    drm/amd/powerplay: reduce sample period time

    for power readings.

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

The theoretical sampling period is from 50ms to 4sec, original 2sec
is long but correct, and 20ms is too short. change it to more
reasonable 200ms.

Signed-off-by: Eric Huang <JinHuiEric.Huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c

@@ -3374,7 +3374,8 @@ static int smu7_get_gpu_power(struct pp_hwmgr *hwmgr,
 			"Failed to start pm status log!",
 			return -1);
 
-	msleep_interruptible(20);
+	/* Sampling period from 50ms to 4sec */
+	msleep_interruptible(200);
 
 	PP_ASSERT_WITH_CODE(!smum_send_msg_to_smc(hwmgr,
 			PPSMC_MSG_PmStatusLogSample),