[media] radio-si470x-i2c: fix a warning on ia64

on ia64, those warnings appear:
	drivers/media/radio/si470x/radio-si470x-i2c.c:470:12: warning: 'si470x_i2c_suspend' defined but not used [-Wunused-function]
	drivers/media/radio/si470x/radio-si470x-i2c.c:487:12: warning: 'si470x_i2c_resume' defined but not used [-Wunused-function]
They're caused because the PM logic uses this define:
	#define SET_SYSTEM_SLEEP_PM_OPS()
With is only defined for CONFIG_PM_SLEEP.
So, change the logic there to test for CONFIG_PM_SLEEP, instead of
CONFIG_PM.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/radio/si470x/radio-si470x-i2c.c

@@ -463,7 +463,7 @@ static int si470x_i2c_remove(struct i2c_client *client)
 }
 
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 /*
  * si470x_i2c_suspend - suspend the device
  */
@@ -509,7 +509,7 @@ static struct i2c_driver si470x_i2c_driver = {
 	.driver = {
 		.name		= "si470x",
 		.owner		= THIS_MODULE,
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 		.pm		= &si470x_i2c_pm,
 #endif
 	},