ar71xx: WNR612v2: fix kernel panic due to wrong Wifi LED init

ar71xx: WNR612v2: fix kernel panic due to wrong Wifi LED init

Netgear WNR612v2 flashed with recent OpenWrt builds suffers from kernel
panic at boot during wireless chip initialization, making device
unusable:

 ath: phy0: Ignoring endianness difference in EEPROM magic bytes.
 ath: phy0: Enable LNA combining
 CPU 0 Unable to handle kernel paging request at virtual address 1000fee1, epc == 801d08f0, ra == 801d0d90
 Oops[#1]:
 CPU: 0 PID: 469 Comm: kmodloader Not tainted 4.9.120 #0
 [ ... register dump etc ... ]
 Kernel panic - not syncing: Fatal exception
 Rebooting in 1 seconds..

This simple patch fixes above error. It keeps LED table in memory after
kernel init phase for ath9k driver to operate correctly (__initdata
removed).

Also, another bug is fixed - correct array size is provided to function
that adds platform LEDs (this device has only 1 connected to Wifi chip)
preventing code from going outside array bounds.

Fixes: 1f5ea4eae46e ("ar71xx: add correct named default wireless led by using platform leds")
Signed-off-by: Michal Cieslakiewicz <michal.cieslakiewicz@wp.pl>
[trimmed commit message]
Signed-off-by: Mathias Kresin <dev@kresin.me>