weston: add Digi custom background

This commit modifies the weston ini file to support a custom
background and includes a new one with Digi branding.

Signed-off-by: Arturo Buzarra <arturo.buzarra@digi.com>

meta-digi-dey/recipes-graphics/wayland/weston_%.bbappend

@@ -0,0 +1,23 @@
+# Copyright (C) 2019 Digi International.
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
+
+SRC_URI += " \
+    file://digi_background.png \
+"
+
+do_install_append() {
+    # Add custom background image
+    install -d ${D}${datadir}/weston
+    install ${WORKDIR}/digi_background.png ${D}${datadir}/weston
+
+    # Customize weston ini file
+    cat <<EOF >>${D}${sysconfdir}/xdg/weston/weston.ini
+
+[shell]
+background-image=/usr/share/weston/digi_background.png
+background-type=scale-crop
+EOF
+}
+
+FILES_${PN} += "${datadir}/weston/digi_background.png"