initramfs-firmware-rb3gen2-image: add firmware image (#827)

Add initramfs image with the firmware for the RB3 Gen2 board.

Author: lumag

recipes-bsp/images/initramfs-firmware-rb3gen2-image.bb

@@ -0,0 +1,7 @@
+DESCRIPTION = "Tiny ramdisk image with RB3-Gen2 firmware files"
+
+PACKAGE_INSTALL += " \
+    packagegroup-rb3gen2-firmware \
+"
+
+require initramfs-firmware-image.inc