sc16is7xx: move label 'err_spi' to correct section

err_spi is used when SERIAL_SC16IS7XX_SPI is enabled, so make
the label only available under SERIAL_SC16IS7XX_SPI option.
Otherwise, the below warning appears.

drivers/tty/serial/sc16is7xx.c:1523:1: warning: label ‘err_spi’ defined but not used [-Wunused-label]
 err_spi:
  ^~~~~~~
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Fixes: ac0cdb3d ("sc16is7xx: missing unregister/delete driver on error in sc16is7xx_init()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/sc16is7xx.c

@@ -1520,10 +1520,12 @@ static int __init sc16is7xx_init(void)
 #endif
 	return ret;
 
+#ifdef CONFIG_SERIAL_SC16IS7XX_SPI
 err_spi:
 #ifdef CONFIG_SERIAL_SC16IS7XX_I2C
 	i2c_del_driver(&sc16is7xx_i2c_uart_driver);
 #endif
+#endif
 err_i2c:
 	uart_unregister_driver(&sc16is7xx_uart);
 	return ret;