staging: hv: fix a kernel warning in netvsc_linkstatus_callback()

netif_notify_peers() caused a kernel warning in netvsc_linkstatus_callback(),
because netvsc_linkstatus_callback() is within IRQ context. So we move
the first call to netif_notify_peers() into queued work as well, but with
zero delay.

In addition to "staging-next", this should also be back-ported to stable
kernels 2.6.32 and later.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>