Bump buidlroot version to 2018.02.6

bsp/buildroot/package/rpi-wifi-firmware/Config.in

@@ -0,0 +1,10 @@
+config BR2_PACKAGE_RPI_WIFI_FIRMWARE
+	bool "rpi-wifi-firmware"
+	depends on BR2_arm || BR2_aarch64
+	select BR2_PACKAGE_LINUX_FIRMWARE
+	select BR2_PACKAGE_LINUX_FIRMWARE_BRCM_BCM43XXX # runtime
+	help
+	  Raspberry Pi 3 and Zero W Broadcom BCM43430 wifi module
+	  NVRAM data.
+
+	  https://github.com/RPi-Distro/firmware-nonfree/

bsp/buildroot/package/rpi-wifi-firmware/rpi-wifi-firmware.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256  872fde4f9942d9aba805880d6eaddfe050305626fd58ad955bfe77c04f6b75a5  brcmfmac43430-sdio.txt

bsp/buildroot/package/rpi-wifi-firmware/rpi-wifi-firmware.mk

@@ -0,0 +1,23 @@
+################################################################################
+#
+# rpi-wifi-firmware
+#
+################################################################################
+
+RPI_WIFI_FIRMWARE_VERSION = 54bab3d6a6d43239c71d26464e6e10e5067ffea7
+# brcmfmac43430-sdio.bin comes from linux-firmware
+RPI_WIFI_FIRMWARE_SOURCE = brcmfmac43430-sdio.txt
+# git repo contains a lot of unrelated files
+RPI_WIFI_FIRMWARE_SITE = https://raw.githubusercontent.com/RPi-Distro/firmware-nonfree/$(RPI_WIFI_FIRMWARE_VERSION)/brcm80211/brcm
+RPI_WIFI_FIRMWARE_LICENSE = PROPRIETARY
+
+define RPI_WIFI_FIRMWARE_EXTRACT_CMDS
+	cp $(DL_DIR)/$($(PKG)_SOURCE) $(@D)/
+endef
+
+define RPI_WIFI_FIRMWARE_INSTALL_TARGET_CMDS
+	$(INSTALL) -D -m 0644 $(@D)/$(RPI_WIFI_FIRMWARE_SOURCE) \
+		$(TARGET_DIR)/lib/firmware/brcm/$(RPI_WIFI_FIRMWARE_SOURCE)
+endef
+
+$(eval $(generic-package))