spice-widget-egl: Declare and initialise "tex" and "verts" shortly

Just syntax change.
Reduce code to initialise these matrices.

Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
Acked-by: Victor Toso <victortoso@redhat.com>
2 jobs for master in 4 minutes and 20 seconds
Status Job ID Name Coverage
  Test
passed #440345
fedora

00:03:40

passed #440346
windows

00:04:18