wcnss: invoke subsystem restart from interrupt context

when subsystem restart is invoked from a workqueue context, there is
a small window of failure where in the APPS can go to suspend before
invoking subsystem restart.  So invoke subystem restart from the
interrupt context itself.

Change-Id: Iacb1f7dbdea994f76ddb8cfa5161a4937f5da5d5
CRs-Fixed: 371744
Signed-off-by: Sameer Thalappil <sameert@codeaurora.org>