drm/amd/powerplay: Allow changing of fan_control in smu_v11_0

[Why]
Before this change, the fan control state on smu_v11 was not able to be
changed because the capability check for checking if the fan control
capability existed was inverted.

[How]
The capability check for fan control in smu_v11_0_auto_fan_control was
inverted, to correctly check for the absence, instead of presence of fan
control capabilities.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Matt Coffin <mcoffin13@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>