USB: gadget: ether needs to select CRC32

Fix build error, ether uses/needs to select CRC32 config symbol:

ether.c:(.text+0x271480): undefined reference to `crc32_le'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -627,6 +627,7 @@ config USB_AUDIO
 config USB_ETH
 	tristate "Ethernet Gadget (with CDC Ethernet support)"
 	depends on NET
+	select CRC32
 	help
 	  This driver implements Ethernet style communication, in one of
 	  several ways: