usb: increase the length of the request buffer

Increase the length of the request buffer.
Current value is not enough for an average
device descriptor.

Signed-off-by: Johann Fischer <j.fischer@phytec.de>
diff --git a/subsys/usb/Kconfig b/subsys/usb/Kconfig
index aac6b78..b41dded 100644
--- a/subsys/usb/Kconfig
+++ b/subsys/usb/Kconfig
@@ -63,7 +63,7 @@
 	range 8 65536
 	default 256 if USB_DEVICE_NETWORK_RNDIS
 	default 1024 if USB_DEVICE_LOOPBACK
-	default 64
+	default 128
 
 config USB_DEVICE_SOF
 	bool "Enable Start of Frame processing in events"