pwm: imx: add Kconfig support

add Kconfig support for this driver.

Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Martyn Welch <martyn.welch@collabora.co.uk>
diff --git a/configs/dms-ba16_defconfig b/configs/dms-ba16_defconfig
index f98088d..fbf1f89 100644
--- a/configs/dms-ba16_defconfig
+++ b/configs/dms-ba16_defconfig
@@ -40,6 +40,7 @@
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_PHYLIB=y
 CONFIG_MII=y
+CONFIG_PWM_IMX=y
 CONFIG_SPI=y
 CONFIG_MXC_SPI=y
 CONFIG_USB=y