usb: musb: export musb_interrupt symbol

currently that's used by another module
(am35x) which, granted, it shouldn't be
using that, but in order to avoid compile
errors, let's export that symbol temporarily
until re-factoring work is done on that
driver.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_core.c

@@ -1628,7 +1628,7 @@ irqreturn_t musb_interrupt(struct musb *musb)
 
 	return retval;
 }
-
+EXPORT_SYMBOL_GPL(musb_interrupt);
 
 #ifndef CONFIG_MUSB_PIO_ONLY
 static int __initdata use_dma = 1;