sonypi: suspend/resume callbacks should be conditionally compiled on CONFIG_PM_SLEEP

This will fix warnings like following when CONFIG_PM_SLEEP is not set:

        warning: 'xxx_suspend' defined but not used [-Wunused-function]
        warning: 'xxx_resume' defined but not used [-Wunused-function]

Because
	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)

Only references the callbacks on CONFIG_PM_SLEEP (instead of CONFIG_PM).

Cc: Mattia Dongili <malattia@linux.it>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>