firmware-utils/mktplinkfw: add description for -W option into usage output

Add description for -W <hwrev> option into usage output of mktplinkfw.

Signed-off-by: yousong <yszhou4tech@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@36497 3c298f89-4303-0410-b956-a3cf2f4a3e73
ar71xx: rename WNR2000v3 support patch

Update the numbering of kernel patch for supporting
Netgear WNR2000v3 from 617 to 618.

Signed-off-by: yousong <yszhou4tech@gmail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@36498 3c298f89-4303-0410-b956-a3cf2f4a3e73