flavours/linux: Add meta-java layer

This is required by meta-openharmony layer.

Signed-off-by: Esben Haabendal <esben.haabendal@huawei.com>

flavours/linux/bblayers.conf.sample

@@ -33,4 +33,5 @@ BBLAYERS ?= " \
   ##OEROOT##/../meta-security \
   ##OEROOT##/../meta-riscv \
   ##OEROOT##/../meta-rauc \
+  ##OEROOT##/../meta-java \
   "