mmc: sdhci-esdhc-imx: add missing inclusion of linux/module.h

There are the following warnings and errorx when compiling the driver.
The patch adds the missing inclusion of linux/module.h to fix them.

drivers/mmc/host/sdhci-esdhc-imx.c:563:12: error: ‘THIS_MODULE’ undeclared here (not in a function)
[..]
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-esdhc-imx.c

@@ -16,6 +16,7 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/gpio.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>