backfire: ar71xx: Configure WNDR3700 switch LED colors properly (backport of r23879)

backfire: ar71xx: Configure WNDR3700 switch LED colors properly (backport of r23879)

For WNDR3700, use green for 1Gb/s and amber for 100Mb/s and 10Mb/s on
the four LAN port switch LEDs. The LEDs will be lit to indicate a link
and will blink to indicate activity. This matches the stock firmware
and the description printed on the label on the unit's underside.

Signed-off-by: Mark Mentovai <mark@moxienet.com>
git-svn-id: svn://svn.openwrt.org/openwrt/branches/backfire@24960 3c298f89-4303-0410-b956-a3cf2f4a3e73