net/usb: remove default in Kconfig for sierra_net driver

The following patch removes the default from the Kconfig entry for sierra_net
driver as recommended.
Signed-off-by: Elina Pasheva <epasheva@sierrawireless.com>
Signed-off-by: Rory Filer <rfiler@sierrawireless.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/Kconfig

@@ -400,7 +400,6 @@ config USB_IPHETH
 config USB_SIERRA_NET
 	tristate "USB-to-WWAN Driver for Sierra Wireless modems"
 	depends on USB_USBNET
-	default y
 	help
 	  Choose this option if you have a Sierra Wireless USB-to-WWAN device.