[ARM] sharpsl_pm: fix compilation w/o CONFIG_PM

Fix compilation of sharpsl_pm when CONFIG_PM in unselected.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Eric Miao <eric.miao@marvell.com>