soc: ti: pm33xx: Make two symbols static

Fix sparse warnings:

drivers/soc/ti/pm33xx.c:144:27: warning: symbol 'rtc_wake_src' was not declared. Should it be static?
drivers/soc/ti/pm33xx.c:160:5: warning: symbol 'am33xx_rtc_only_idle' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/soc/ti/pm33xx.c

@@ -141,7 +141,7 @@ static int __init am43xx_map_gic(void)
 }
 
 #ifdef CONFIG_SUSPEND
-struct wkup_m3_wakeup_src rtc_wake_src(void)
+static struct wkup_m3_wakeup_src rtc_wake_src(void)
 {
 	u32 i;
 
@@ -157,7 +157,7 @@ struct wkup_m3_wakeup_src rtc_wake_src(void)
 	return rtc_ext_wakeup;
 }
 
-int am33xx_rtc_only_idle(unsigned long wfi_flags)
+static int am33xx_rtc_only_idle(unsigned long wfi_flags)
 {
 	omap_rtc_power_off_program(&omap_rtc->dev);
 	am33xx_do_wfi_sram(wfi_flags);