[PATCH] shpchp: fix improper write to Command Completion Detect bit

Current SHPCHP driver writes a '0' to the Command Completion Detect
bit to clear the Command Complete Interrupt Pending. But according to
the SHPC spec (See 4.7.3.1 System Interrupts), SHPCHP driver must
write '1'. This patch fixes this bug.

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