spi: omap2-mcspi: remove duplicated include from spi-omap2-mcspi.c

Remove duplicated include.
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-omap2-mcspi.c

@@ -39,7 +39,6 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/pinctrl/consumer.h>
-#include <linux/err.h>
 
 #include <linux/spi/spi.h>