trats/trats2: exynos_power_init: return 0 if no battery detected.

Generic board support is now enabled for Exynos 4, and if any
init function returns an error then the init process is stopped.

This makes a boot issue on the Trats and Trats2 devices. If the device
is supplied by USB cable or an external power supply then it can't boot
because function exynos_power_init returns an error. Now this function
returns 0 if battery is not connected.
Signed-off-by: NPrzemyslaw Marczak <p.marczak@samsung.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Piotr Wilczek <p.wilczek@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Signed-off-by: NMinkyu Kang <mk7.kang@samsung.com>

board/samsung/trats/trats.c

@@ -332,7 +332,7 @@ int exynos_power_init(void)
 
 	if (!p_chrg->chrg->chrg_bat_present(p_chrg)) {
 		puts("No battery detected\n");
-		return -1;
+		return 0;
 	}
 
 	p_fg->fg->fg_battery_check(p_fg, p_bat);

board/samsung/trats2/trats2.c

@@ -214,7 +214,7 @@ int exynos_power_init(void)
 
 	if (!p_chrg->chrg->chrg_bat_present(p_chrg)) {
 		puts("No battery detected\n");
-		return -1;
+		return 0;
 	}
 
 	p_fg->fg->fg_battery_check(p_fg, p_bat);