mel.conf: remove xserver dependency on emgd

Since the emgd-driver-bin package requires white-listing the EMGD
license, remove xserver dependency on emgd and use recipes from Poky.

Signed-off-by: Fahad Arslan <fahad_arslan@mentor.com>
Merge pull request #90 from fahadarslan/sb-1944

mel.conf: remove xserver dependency on emgd