mediatek: device tree overlay for BPI-R4 with BE14 module

Some Banana Pi BPI-R4 BE14 WiFi modules are shipped with zeroed
tx_power fields in EEPROM (2G/5G/6G). This leads to low transmit power
on affected bands.
This overlay provides known-good EEPROM data (including correct tx_power
values for 2G/5G/6G bands) dumped from a working BE14 module.

To enable BE14 overlay, add into u-boot bootconf_extra
parameter: 'mt7988a-bananapi-bpi-r4-wifi-be14'.
You can use example script:

    overlay="mt7988a-bananapi-bpi-r4-wifi-be14"
    current="$(fw_printenv -n bootconf_extra 2>/dev/null)"
    if [ -n "${current}" ]; then
        fw_setenv bootconf_extra "${current}#${overlay}"
    else
        fw_setenv bootconf_extra "${overlay}"
    fi

Earlier proposal proposed in [1] was fallback to default values if
invalid EEPROM content is detected.

[1] openwrt/openwrt#19503

Fixes: openwrt/openwrt#17489
Signed-off-by: Daniel Pawlik <pawlik.dan@gmail.com>

Author: danpawlik

target/linux/mediatek/image/filogic.mk

@@ -671,7 +671,7 @@ define Device/bananapi_bpi-r4-common
   DEVICE_VENDOR := Bananapi
   DEVICE_DTS_DIR := $(DTS_DIR)/
   DEVICE_DTS_LOADADDR := 0x45f00000
-  DEVICE_DTS_OVERLAY:= mt7988a-bananapi-bpi-r4-emmc mt7988a-bananapi-bpi-r4-rtc mt7988a-bananapi-bpi-r4-sd
+  DEVICE_DTS_OVERLAY:= mt7988a-bananapi-bpi-r4-emmc mt7988a-bananapi-bpi-r4-rtc mt7988a-bananapi-bpi-r4-sd mt7988a-bananapi-bpi-r4-wifi-be14
   DEVICE_DTC_FLAGS := --pad 4096
   DEVICE_PACKAGES := kmod-hwmon-pwmfan kmod-i2c-mux-pca954x kmod-eeprom-at24 kmod-mt7996-firmware kmod-mt7996-233-firmware \
 		     kmod-rtc-pcf8563 kmod-sfp kmod-phy-aquantia kmod-usb3 e2fsprogs f2fsck mkf2fs mt7988-wo-firmware