dfu: add support for the dfu_alt_info reintialization from the flashed script

Reinitialize DFU USB gadget after flashing the 'SCRIPT' entity to ensure
that the potential changes to the 'dfu_alt_info' environment variable are
applied.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
[lukma - I've moved the bool retry to avoid build (CI) errors]
diff --git a/common/dfu.c b/common/dfu.c
index d23cf67..16bd1ba 100644
--- a/common/dfu.c
+++ b/common/dfu.c
@@ -98,6 +98,9 @@
 		}
 #endif
 
+		if (dfu_reinit_needed)
+			goto exit;
+
 		WATCHDOG_RESET();
 		usb_gadget_handle_interrupts(usbctrl_index);
 	}