PM / QoS: remove duplicate call to pm_qos_update_target

In 3.10.y backport patch 1dba3037,
the logic to call pm_qos_update_target was moved to __pm_qos_update_request.
However, the original code was left in function pm_qos_update_request.

Currently, if pm_qos_update_request is called where new_value !=
req->node.prio then pm_qos_update_target will be called twice in a row.
Once in pm_qos_update_request and then again in the following call to
_pm_qos_update_request.

Removing the left over code from pm_qos_update_request stops this second
call to pm_qos_update_target where the work of removing / re-adding the
new_value in the constraints list would be duplicated.

Signed-off-by: Michael Scott <michael.scott@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>