power: twl4030: Add CONFIG_CMD_POWEROFF support

With the addition of twl4030_power_off(), let's allow the 'poweroff' command
to run this function when CONFIG_CMD_POWEROFF is enabled.

Tested on a DM3730 with twl4030 PMIC.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>

drivers/power/twl4030.c

@@ -171,3 +171,12 @@ void twl4030_power_mmc_init(int dev_index)
 		mdelay(100);	/* ramp-up delay from Linux code */
 	}
 }
+
+#ifdef CONFIG_CMD_POWEROFF
+int do_poweroff(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	twl4030_power_off();
+
+	return 0;
+}
+#endif