ide: allow ide_dev_read_id() to be called from the IRQ context
* Un-static __ide_wait_stat().
* Allow ide_dev_read_id() helper to be called from the IRQ context by
adding irq_ctx flag and using mdelay()/__ide_wait_stat() when needed.
* Switch ide_driveid_update() to set irq_ctx flag.
This change is needed for the consecutive patch which fixes races in
handling of user-space SET XFER commands but for improved bisectability
and clarity it is better to do it in a separate patch.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>