disp: msm: sde: remove previous pm qos irq vote during affinity change

In the current code during affinity change, irq cpu mask is
being updated without clearing previous pm qos vote. Due to
this, even after entering idle state, qos vote is still
present on other cpus. This change clears previous pm qos
vote before adding another.

Change-Id: Ic0326a09d37d03d5a8b0444362a6f1492993040c
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>