Make imx recipes depend on freescale layer

In order to use this layer without hard dependency to the freescale
layer. The freescale layer is only necessary to build HW23 images.

BugzID: 69469

conf/layer.conf

@@ -6,6 +6,7 @@ BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \
 	    ${LAYERDIR}/recipes-*/*/*.bbappend"
 
 BBFILES_DYNAMIC += "meta-ublox-modules:${LAYERDIR}/bbappends/ublox-module/recipes-*/*/*.bbappend"
+BBFILES_DYNAMIC += "meta-freescale:${LAYERDIR}/freescale/recipes-*/*/*.bb*"
 
 
 BBFILE_COLLECTIONS += "netmodule-bsp"