drm/amdgpu: return from atombios_dp_get_dpcd only when error

In amdgpu_connector_hotplug(), we need to start DP link
training only after we have received DPCD. The function
amdgpu_atombios_dp_get_dpcd() returns non-zero value only
when an error condition is met, otherwise returns zero.
So in case the function encounters an error, we need to
skip rest of the code and return from amdgpu_connector_hotplug()
immediately. Only when we are successfull in reading DPCD
pin, we should carry on with turning-on the monitor.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c

@@ -77,7 +77,7 @@ void amdgpu_connector_hotplug(struct drm_connector *connector)
 			} else if (amdgpu_atombios_dp_needs_link_train(amdgpu_connector)) {
 				/* Don't try to start link training before we
 				 * have the dpcd */
-				if (!amdgpu_atombios_dp_get_dpcd(amdgpu_connector))
+				if (amdgpu_atombios_dp_get_dpcd(amdgpu_connector))
 					return;
 
 				/* set it to OFF so that drm_helper_connector_dpms()