[PATCH] shpchp: fix improper wait for command completion

Current SHPCHP driver uses msleep_interruptible() function to wait for
a command completion event. But I think this would cause an unnecessary
long wait until timeout, if command completion interrupt came before
task state was changed to TASK_INTERRUPTIBLE. This patch fixes this
issue. With this patch, command completion becomes faster as follows:

o Without this patch

	# time echo 1 > power

	real    0m4.708s
	user    0m0.000s
	sys     0m0.524s

o With this patch

	# time echo 1 > power

	real    0m2.221s
	user    0m0.000s
	sys     0m0.532s

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