usb: gadget: nokia: include f_ecm.c

recent changes to gadget framework have
exposed a flaw in nokia.c where it uses
f_ecm.c but it wasn't including it like
other gadget drivers.

This is a temporary patch until all other
function drivers are converted to new API
where each function driver becomes a module
and binding is done through configfs.

Solves a linking error when building g_nokia.ko

Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/nokia.c

@@ -38,6 +38,7 @@
  * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
  */
 #define USBF_OBEX_INCLUDED
+#include "f_ecm.c"
 #include "f_obex.c"
 #include "f_phonet.c"
 #include "u_ether.c"