purism: librem5: Fix a function declaration in spl.c

Here we implement usb_gadget_handle_interrupts() but did not include
<linux/usb/gadget.h> so did not have the declaration correct. Fix this
and add the missing include.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/purism/librem5/spl.c b/board/purism/librem5/spl.c
index 1a203b4..90f1fcf 100644
--- a/board/purism/librem5/spl.c
+++ b/board/purism/librem5/spl.c
@@ -26,6 +26,7 @@
 #include <usb.h>
 #include <dwc3-uboot.h>
 #include <linux/delay.h>
+#include <linux/usb/gadget.h>
 #include "librem5.h"
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -417,7 +418,7 @@
 	return rv;
 }
 
-int usb_gadget_handle_interrupts(void)
+int usb_gadget_handle_interrupts(int index)
 {
 	dwc3_uboot_handle_interrupt(0);
 	return 0;