wma_roam_event_callback can get called in atomic context from
wma_wake_event_piggybacked for reason WMI_ROAM_REASON_HO_FAILED
which lead to acquiring of pm_ctx->qdf_conc_list_lock mutex lock
in atomic context.
To fix this post msg to scheduler thread to call the policy mgr
API in scheduler thread context
Change-Id: I6b75de64a33559b73a7edc73e1100cfb3a1f507d
CRs-Fixed: 2491147
a227e75e12