plnx-deploy.bbclass: Using variable to specify the QEMU hw dtb
plnx-deploy.bbclass: Using variable to specify the QEMU hw dtb

This patch will add support to specify the QEMU hw dtb files specific to
bsp name.

Signed-off-by: Raju Kumar Pothuraju <faf499088bbd7c813560772aeae4b5ae1c5f96a7@xilinx.com>
Signed-off-by: Sai Hari Chandana Kalluri <dcd6f85a7bffd89d026445db0f5113d6d436d06a@xilinx.com>

Xilinx/meta-petalinux,Xilinx/meta-petalinux,Xilinx/meta-petalinux,Xilinx/meta-petalinux,Xilinx/meta-petalinux,Xilinx/meta-petalinux