serial: imx: drop check for enabled dma in .startup

imx_shutdown() calls imx_disable_dma if .dma_is_enabled. So after
imx_shudown() completes, .dma_is_enabled is zero. For this reason
.dma_is_enabled is also zero when imx_startup() is called. So the check
for this variable being zero can be dropped.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: NShawn Guo <shawnguo@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -1257,7 +1257,7 @@ static int imx_startup(struct uart_port *port)
 	writel(USR1_RTSD | USR1_DTRD, sport->port.membase + USR1);
 	writel(USR2_ORE, sport->port.membase + USR2);
 
-	if (dma_is_inited && !sport->dma_is_enabled)
+	if (dma_is_inited)
 		imx_enable_dma(sport);
 
 	temp = readl(sport->port.membase + UCR1) & ~UCR1_RRDYEN;