[RPI] add layer configuration files

conf/bblayers.conf

+
+# Layers used for RaspberryPi boards
+BBLAYERS += "\
+  ${BSPDIR}/layers/meta-seco-bsp \
+  ${BSPDIR}/layers/meta-seco-rpi \
+  ${BSPDIR}/layers/meta-raspberrypi \
+"

conf/layer.conf

+# We have a conf and classes directory, add to BBPATH
+BBPATH .= ":${LAYERDIR}"
+
+RKBASE = '${@os.path.normpath("${LAYERDIR}")}'
+
+# We have recipes-* directories, add to BBFILES
+BBFILES += "${LAYERDIR}/recipes-*/*/*.bb ${LAYERDIR}/recipes-*/*/*.bbappend"
+
+BBFILE_COLLECTIONS += "seco-rpi"
+
+BBFILE_PATTERN_seco-rpi := "^${LAYERDIR}/"
+BBFILE_PRIORITY_seco-rpi = "9"
+
+LAYERDEPENDS_seco-imx = "seco-bsp"
+
+# This should only be incremented on significant changes that will
+# cause compatibility issues with other layers
+LAYERVERSION_seco-rpi = "1"
+LAYERSERIES_COMPAT_seco-rpi = "kirkstone"
+
+DISABLE_SPLASH = "1"
+DISABLE_OVERSCAN = "1"
+
+RPI_EXTRA_CONFIG = "\
+display_auto_detect=1\n\
+arm_boost=1\n\
+"