xen/manage: Fix suspend error path

The device power management API has the following asymmetry:
* dpm_suspend_start() does not clean up on failure
  (it requires a call to dpm_resume_end())
* dpm_suspend_end() does clean up on failure
  (it does not require a call to dpm_resume_start())

The asymmetry was introduced by commit d8f3de0d ("Suspend-related
patches for 2.6.27") in June 2008:  It removed a call to device_resume()
from device_suspend() (which was later renamed to dpm_suspend_start()).

When Xen began using the device power management API in May 2008 with
commit 0e91398f ("xen: implement save/restore"), the asymmetry did
not yet exist.  But since it was introduced, a call to dpm_resume_end()
is missing in the error path of dpm_suspend_start().  Fix it.

Fixes: d8f3de0d ("Suspend-related patches for 2.6.27")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org  # v2.6.27
Reviewed-by: "Rafael J. Wysocki (Intel)" <rafael@kernel.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <22453676d1ddcebbe81641bb68ddf587fee7e21e.1756990799.git.lukas@wunner.de>