isci: fix reset timeout handling

isci: fix reset timeout handling

commit ddfadd7736b677de2d4ca2cd5b4b655368c85a7a upstream.

Remove an erroneous BUG_ON() in the case of a hard reset timeout.  The
reset timeout handler puts the port into the "awaiting link-up" state.
The timeout causes the device to be disconnected and we need to be in
the awaiting link-up state to re-connect the port.  The BUG_ON() made
the incorrect assumption that resets never timeout and we always
complete the reset in the "resetting" state.

Testing this patch also uncovered that libata continues to attempt to
reset the port long after the driver has torn down the context.  Once
the driver has committed to abandoning the link it must indicate to
libata that recovery ends by returning -ENODEV from
->lldd_I_T_nexus_reset().

Acked-by: Lukasz Dorau <lukasz.dorau@intel.com>
Reported-by: David Milburn <dmilburn@redhat.com>
Reported-by: Xun Ni <xun.ni@intel.com>
Tested-by: Xun Ni <xun.ni@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>