matrix-gui: updating to use latest source revision

matrix-gui: updating to use latest source revision

* Use latest source revision 131
* Add platform support for multiple platforms
* Remove un-used files from SRC_URI and repository.
    * init files are now part of the matrix repository
    * matrix-gui.desktop is now part of the matrix repository
    * the cursor override patch is now in the matrix sources
* Bumped SRCREV to 136 in version 3 of this patch

Signed-off-by: Chase Maupin <chase.maupin@ti.com>
Signed-off-by: Jeff Lance <j-lance1@ti.com>
Acked-by: Denys Dmytriyenko <denis@denix.org>
Signed-off-by: Denys Dmytriyenko <denis@denix.org>