fb_deferred_io_work() can access the vmbus ringbuffer by calling
fbdefio->deferred_io() -> synthvid_deferred_io() -> synthvid_update().

Because the vmbus ringbuffer is inaccessible between hvfb_suspend()
and hvfb_resume(), we must cancel info->deferred_work before calling
vmbus_close() and then reschedule it after we reopen the channel
in hvfb_resume().

Fixes: a4ddb11d297e ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")
Fixes: 824946a8b6fb ("video: hyperv_fb: Add the support of hibernation")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Wei Hu <weh@microsoft.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>