ipq806x: add a helper variable with the vendor name stripped

This will allow to maintain the current syntax for LEDs config
when switching to a device tree compatible string boardname.

None of the current boards use a comma in the boardname, so they
will be unaffected.

Signed-off-by: Luis Araneda <luaraneda@gmail.com>

target/linux/ipq806x/base-files/etc/board.d/01_leds

@@ -8,6 +8,7 @@
 board_config_update
 
 board=$(board_name)
+boardname="${board##*,}"
 
 case "$board" in
 c2600)