image: Add machine into mount points path

We need to add also machine name into buildchroot mount point names to
prevent conflicts between different machines with the same distro, arch
and image types.

Signed-off-by: Anton Mikanovich <amikan@ilbers.de>

meta/classes/image.bbclass

@@ -28,7 +28,7 @@ INITRD_IMAGE ?= "${IMAGE_FULLNAME}-initrd.img"
 DTB_FILES ?= ""
 
 # Useful variables for imager implementations:
-PP = "/home/builder/${PN}-${IMAGE_SUFFIX}"
+PP = "/home/builder/${PN}-${MACHINE}-${IMAGE_SUFFIX}"
 PP_DEPLOY = "${PP}/deploy"
 PP_ROOTFS = "${PP}/rootfs"
 PP_WORK = "${PP}/work"