infiniband: Only include mutex.h once in drivers/infiniband/hw/cxgb4/iw_cxgb4.h

Only include the header linux/mutex.h once inside
drivers/infiniband/hw/cxgb4/iw_cxgb4.h
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

@@ -46,7 +46,6 @@
 #include <linux/timer.h>
 #include <linux/io.h>
 #include <linux/kfifo.h>
-#include <linux/mutex.h>
 
 #include <asm/byteorder.h>