msm_11ad: clear affinity hint upon low bus request

When driver calls ops_bus_request with high bandwidth requirement,
affinity of wil6210 interrupt is set to first big core. However this
setting is not cleared when driver lowers bandwidth requirement.
This causes WARN_ON_ONCE(desc->affinity_hint) upon wil6210 rmmod.

Fix this by clearing affinity hint upon low bandwidth request.

Change-Id: I87b6b7ec9b369b84a9d3724d92a821a1302d1f83
Signed-off-by: Dedy Lansky <dlansky@codeaurora.org>