net-tools: Place package content as per bitbake environment.
net-tools Makefile was hardcoded sbin, bin installation paths to /bin and /sbin
respectively. This change moves the installed files to appropriate location as
per configured bitbake environment.
This might be solved much better way by patching Makefile, but that causing
build issues, as net-tools recipe is using pre-generated config.{h/status}.
