drm/amd/pm/smu11: Prevent division by zero

The user can set any speed value.
If speed is greater than UINT_MAX/8, division by zero is possible.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1e866f1 ("drm/amd/pm: Prevent divide by zero")
Signed-off-by: Denis Arefev <arefev@swemel.ru>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit da7dc71)
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c

@@ -1204,7 +1204,7 @@ int smu_v11_0_set_fan_speed_rpm(struct smu_context *smu,
 	uint32_t crystal_clock_freq = 2500;
 	uint32_t tach_period;
 
-	if (speed == 0)
+	if (!speed || speed > UINT_MAX/8)
 		return -EINVAL;
 	/*
 	 * To prevent from possible overheat, some ASICs may have requirement