iscsi: fix build errors when linux/phy*.h is removed from net/dsa.h

drivers/target/iscsi/iscsi_target_login.c:1135:7: error: implicit declaration of function 'try_module_get' [-Werror=implicit-function-declaration]

Add linux/module.h to iscsi_target_login.c.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Acked-by: NNicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/target/iscsi/iscsi_target_login.c

@@ -17,6 +17,7 @@
  ******************************************************************************/
 
 #include <crypto/hash.h>
+#include <linux/module.h>
 #include <linux/string.h>
 #include <linux/kthread.h>
 #include <linux/idr.h>