usb: gadget: mv_udc: reduce the delay interval

There are several places use udelay(LOOPS_USEC) to wait the status to be
changed, but the delay interval is a bit too long, so reduce it to
enhance the performance.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/mv_udc_core.c

@@ -53,7 +53,7 @@
 #define READSAFE_TIMEOUT	1000
 #define DTD_TIMEOUT		1000
 
-#define LOOPS_USEC_SHIFT	4
+#define LOOPS_USEC_SHIFT	1
 #define LOOPS_USEC		(1 << LOOPS_USEC_SHIFT)
 #define LOOPS(timeout)		((timeout) >> LOOPS_USEC_SHIFT)