kernel: kmod-usb-serial-keyspan: fix dependencies

This fixes the following error:
keyspan: Unknown symbol ezusb_fx1_ihex_firmware_download (err 0)

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>


git-svn-id: svn://svn.openwrt.org/openwrt@37899 3c298f89-4303-0410-b956-a3cf2f4a3e73