packagegroup-webos-extended: Include dhcp-client only for the emulator

:Release Notes:
This change removes dhcp-client from all targets except the one that
actually uses it: qemux86.

:Detailed Notes:
dhcp-client will be removed entirely once [GF-10079] is implemented.

:Testing Performed:
1) MiniBAT
2) This change was tested as part of the full solution for read-only
   rootfs.

:QA Notes:

:Issues Addressed:
[GF-10080] Only install dhcp-client for the emulator

Open-webOS-DCO-1.0-Signed-off-by: Iyad Qumei <iyad.qumei@lge.com>
Change-Id: Ifa84b1dee8b1d899f69632a7a69ca1463a242330
Reviewed-on: https://g2g.palm.com/2890
Reviewed-by: Build Verification
Reviewed-by: Iyad Qumei <iyad.qumei@lge.com>
Tested-by: Iyad Qumei <iyad.qumei@lge.com>
Reviewed-by: Ed Chejlava <ed.chejlava@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>