pwm: imx: set can_sleep flag for imx_pwm

The .config() hook imx_pwm_config() calls clk APIs like clk_prepare()
and clk_get_rate(), which might sleep, so we need to set can_sleep flag
on pwm_chip.
Signed-off-by: NShawn Guo <shawn.guo@freescale.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-imx.c

@@ -262,6 +262,7 @@ static int imx_pwm_probe(struct platform_device *pdev)
 	imx->chip.dev = &pdev->dev;
 	imx->chip.base = -1;
 	imx->chip.npwm = 1;
+	imx->chip.can_sleep = true;
 
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	imx->mmio_base = devm_ioremap_resource(&pdev->dev, r);