PNP: make pnpacpi_suspend handle errors

pnpacpi_suspend() doesn't check the result returned by
acpi_pm_device_sleep_state() before passing it to acpi_bus_set_power(),
which may not be desirable.   Make it select the target power state of the
device using its second argument if acpi_pm_device_sleep_state() fails.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Looks-ok-to: Pavel Machek <pavel@ucw.cz>
Cc: Adam Belay <ambx1@neo.rr.com>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>