Adding OpenWrt support for Linksys MX5300

Currently, OpenWrt boots from flash memory. The default rootfstype is ubifs, so we need to add rootfstype=squashfs ro to bootargs.

I used BDF files from the FCC directory. Many 5GHz radio frequencies are disabled.
Is there any way to enable disabled frequencies?

Wiphy phy0
		Frequencies:
			* 5180 MHz [36] (disabled)
			* 5200 MHz [40] (disabled)
			* 5220 MHz [44] (disabled)
			* 5240 MHz [48] (disabled)
			* 5260 MHz [52] (disabled)
			* 5280 MHz [56] (disabled)
			* 5300 MHz [60] (disabled)
			* 5320 MHz [64] (disabled)
			* 5500 MHz [100] (24.0 dBm) (radar detection)
			* 5520 MHz [104] (24.0 dBm) (radar detection)
			* 5540 MHz [108] (24.0 dBm) (radar detection)
			* 5560 MHz [112] (24.0 dBm) (radar detection)
			* 5580 MHz [116] (24.0 dBm) (radar detection)
			* 5600 MHz [120] (24.0 dBm) (radar detection)
			* 5620 MHz [124] (24.0 dBm) (radar detection)
			* 5640 MHz [128] (24.0 dBm) (radar detection)
			* 5660 MHz [132] (24.0 dBm) (radar detection)
			* 5680 MHz [136] (24.0 dBm) (radar detection)
			* 5700 MHz [140] (24.0 dBm) (radar detection)
			* 5720 MHz [144] (24.0 dBm) (radar detection)
			* 5745 MHz [149] (30.0 dBm)
			* 5765 MHz [153] (30.0 dBm)
			* 5785 MHz [157] (30.0 dBm)
			* 5805 MHz [161] (30.0 dBm)
			* 5825 MHz [165] (30.0 dBm)
			* 5845 MHz [169] (27.0 dBm) (no IR)
			* 5865 MHz [173] (disabled)
Wiphy phy1
		Frequencies:
			* 5180 MHz [36] (24.0 dBm)
			* 5200 MHz [40] (24.0 dBm)
			* 5220 MHz [44] (24.0 dBm)
			* 5240 MHz [48] (24.0 dBm)
			* 5260 MHz [52] (24.0 dBm) (radar detection)
			* 5280 MHz [56] (24.0 dBm) (radar detection)
			* 5300 MHz [60] (24.0 dBm) (radar detection)
			* 5320 MHz [64] (24.0 dBm) (radar detection)
			* 5500 MHz [100] (disabled)
			* 5520 MHz [104] (disabled)
			* 5540 MHz [108] (disabled)
			* 5560 MHz [112] (disabled)
			* 5580 MHz [116] (disabled)
			* 5600 MHz [120] (disabled)
			* 5620 MHz [124] (disabled)
			* 5640 MHz [128] (disabled)
			* 5660 MHz [132] (disabled)
			* 5680 MHz [136] (disabled)
			* 5700 MHz [140] (disabled)
			* 5720 MHz [144] (disabled)
			* 5745 MHz [149] (disabled)
			* 5765 MHz [153] (disabled)
			* 5785 MHz [157] (disabled)
			* 5805 MHz [161] (disabled)
			* 5825 MHz [165] (disabled)
			* 5845 MHz [169] (disabled)
			* 5865 MHz [173] (disabled)
			* 5885 MHz [177] (disabled)

And I keep getting this error:
[ 1028.315295] hsl_phy_phydev_get[805]:ERROR:phy_addr 5 phydev is NULL