guf-image: Build a tar.gz image

Move the variables IMAGE_BOOT_FILES and IMAGE_FSTYPES to the guf-image
recipe. These were prevoiusly defined in meta-guf-machines but are more
distro options.

The move also sets teh IMAGE_FSTYPE from tar.bz2 to tar.gz.
This was the previous default and according to
https://tukaani.org/lzma/benchmarks.html decompresses faster.

recipes-bsp/images/guf-image.bb

@@ -2,6 +2,10 @@ SUMMARY = "Garz & Fricke Yocto Image"
 
 LICENSE = "MIT"
 
+IMAGE_BOOT_FILES = " uImage "
+
+IMAGE_FSTYPES = " tar.gz "
+
 inherit core-image features_check extrausers
 
 REQUIRED_DISTRO_FEATURES = "wayland"