ipq806x: drop useless uci-defaults compat version script

ipq806x: drop useless uci-defaults compat version script

Drop useless uci-defaults compat version script as it's not needed
anymore and should have been dropped on DSA conversion.

The script was needed for Linksys EA7500 and EA8500 for the kernel space
migration. We now handle compat version setting in board.d scripts.

Having this script with actually the wrong value (2.0) cause upgrade
problem and conflicts with board.d script.

Fixes: 337e36e0ef98 ("ipq806x: convert each device to DSA implementation")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>