layer.conf: prepend instead of append to sort before oe-core in BBPATH

This helps avoid bblayers.conf ordering issues, when temporarily overriding
files from oe-core in meta-ti.

Signed-off-by: Denys Dmytriyenko <denys@ti.com>

conf/layer.conf

@@ -1,5 +1,5 @@
 # We have a conf and classes directory, append to BBPATH
-BBPATH .= ":${LAYERDIR}"
+BBPATH =. "${LAYERDIR}:"
 
 # We have a recipes directory, add to BBFILES
 BBFILES += "${LAYERDIR}/recipes*/*/*.bb ${LAYERDIR}/recipes*/*/*.bbappend"