gmae: remove GMAE toolchain and packagegroups

GMAE (GNOME Mobile And Embedded) doesn't really exist anymore and these packages
were a subset of it anyway.  Remove as they don't give the user anything useful
now that you can generate a SDK from an arbitrary image.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>