[PATCH] shpchp - Fix incorrect return value of interrupt handler

Current SHPCHP driver has a bug in its interrupt handler which cause
"IRQ #: nobody cared" oops. This problem can be reproduced easily by
the following operation.

    # cd /sys/bus/pci/slots/<slot#>
    # while true; do echo 1 > attention ; done &

The reason is that when command complete interrupt is raised, current
SHPCHP driver's interrupt handler returns IRQ_NONE regardless of if
the interrupt is handled or not.

This patch fixes this issue.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>