serial: imx: remove null check of sport in suspend/resume function

platform_get_drvdata always retrun a valid value after probe succeed.

It also fixed smatch warnings:
drivers/tty/serial/imx.c:1376 serial_imx_suspend() warn: variable dereferenced before check 'sport' (see line 1372)
drivers/tty/serial/imx.c:1392 serial_imx_resume() warn: variable dereferenced before check 'sport' (see line 1388)
Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -1373,7 +1373,6 @@ static int serial_imx_suspend(struct platform_device *dev, pm_message_t state)
 	val |= UCR3_AWAKEN;
 	writel(val, sport->port.membase + UCR3);
 
-	if (sport)
 	uart_suspend_port(&imx_reg, &sport->port);
 
 	return 0;
@@ -1389,7 +1388,6 @@ static int serial_imx_resume(struct platform_device *dev)
 	val &= ~UCR3_AWAKEN;
 	writel(val, sport->port.membase + UCR3);
 
-	if (sport)
 	uart_resume_port(&imx_reg, &sport->port);
 
 	return 0;