staging: rtl8712: Declare function as static

Declare rtl871x_intf_resume() function static since it is defined and called
in this file only.

This fixes the following sparse warning:
warning: symbol 'rtl871x_intf_resume' was not declared. Should it be static?
Signed-off-by: NAmitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/usb_intf.c

@@ -221,7 +221,7 @@ static int r871x_suspend(struct usb_interface *pusb_intf, pm_message_t state)
 	return 0;
 }
 
-void rtl871x_intf_resume(struct _adapter *padapter)
+static void rtl871x_intf_resume(struct _adapter *padapter)
 {
 	if (padapter->dvobjpriv.inirp_init)
 		padapter->dvobjpriv.inirp_init(padapter);