usb: musb: musb_host.c: Cleaning up uninitialized variables

There is a risk that the variable will be used without being initialized.

This was largely found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/musb/musb_host.c

@@ -1957,7 +1957,7 @@ static int musb_schedule(
 	struct musb_qh		*qh,
 	int			is_in)
 {
-	int			idle;
+	int			idle = 0;
 	int			best_diff;
 	int			best_end, epnum;
 	struct musb_hw_ep	*hw_ep = NULL;