[CONNECTIVITY] Add recipe: Edimax EW-7611ULB Realtek RTL8723BU firmware

Add Edimax EW-7611ULB USB combo WiFi+BT dongle firmware, to be used with the
kernel built-in driver: its chipset is Realtek RTL8723BU.
The firmware files are sourced from the EW-7611ULB_Linux_Driver_1.0.2 vendor package:
https://www.edimax.com/edimax/mw/cufiles/files/download/Driver_Utility/EW-7611ULB/EW-7611ULB_Linux_Driver_1.0.2.1.zip
* BT binaries have simply been renamed from EW-7611ULB_Linux_Driver_1.0.1.2/Bluetooth/8723BU
* WiFi binaries had to be generated from the convert_firmware{.c,.s} files available into the archive:
  * conversion program adapted from https://github.com/lwfinger/rtl8723bu/blob/master/convert_firmware.c
  * firmware data from EW-7611ULB_Linux_Driver_1.0.1.2/Wi-FI/driver/hal/rtl8723b/hal8723b_fw.c

recipes-connectivity/ew-7611ulb-rtl8723bu-fw/ew-7611ulb-rtl8723bu-fw.bb

+DESCRIPTION = "Edimax EW-7611ULB Realtek RTL8723BU firmware"
+
+LICENSE = "CLOSED"
+RDEPENDS:${PN} += "linux-firmware-rtl-license"
+
+SRC_URI = " \
+    file://firmware-ew-7611ulb.tar.gz \
+"
+
+do_install () {
+    # WiFi fw
+    install -d ${D}/lib/firmware/rtlwifi
+    install -m 0644 ${WORKDIR}/firmware-ew-7611ulb/wifi/rtl8723bu_ap.bin     ${D}/lib/firmware/rtlwifi/
+    install -m 0644 ${WORKDIR}/firmware-ew-7611ulb/wifi/rtl8723bu_nic.bin    ${D}/lib/firmware/rtlwifi/
+    install -m 0644 ${WORKDIR}/firmware-ew-7611ulb/wifi/rtl8723bu_wowlan.bin ${D}/lib/firmware/rtlwifi/
+    # BT fw
+    install -d ${D}/lib/firmware/rtl_bt
+    install -m 0644 ${WORKDIR}/firmware-ew-7611ulb/bt/rtl8723b_fw.bin     ${D}/lib/firmware/rtl_bt/
+    install -m 0644 ${WORKDIR}/firmware-ew-7611ulb/bt/rtl8723b_config.bin ${D}/lib/firmware/rtl_bt/
+}
+
+FILES:${PN} += " \
+    /lib/firmware/rtlwifi/* \
+    /lib/firmware/rtl_bt/* \
+"