Adjust Live Wallpapers window parameters

The pre-configured layout for xlarge screens for the Live Wallpapers
dialog window has some issues on our devices, causing wallpapers to
show up cropped.
This change reconfigures some layout parameters to create a better
display grid.

For: APDEV-2643

Change-Id: Ifc6ce8e9e11e96c9d34bb243917743caec867ee1
Signed-off-by: Tiberiu Breana <tiberiu.a.breana@intel.com>
Reviewed-on: https://android.intel.com/178326
Reviewed-by: Chiras, Robert <robert.chiras@intel.com>
Tested-by: Chiras, Robert <robert.chiras@intel.com>