meta-agl-bsp: imx6: Add EGL support for iMX6 in Weston 2.0

meta-agl-bsp: imx6: Add EGL support for iMX6 in Weston 2.0

In Weston 2.0, the EGL support was dropped from the fbdev-backend,
as that was not the correct way to initialize EGL. However, the
vendor support patches in Weston 1.11 still require that functionality.
Restore the EGL support in the fbdev-backend, until the issue is
resolved, by either adding a standalone backend, or switching to etnaviv.

Bug-AGL: SPEC-905

Change-Id: I9fc00e35c2eefee07998053e1fccec6265ac3b9e
Signed-off-by: Mihail Grigorov <michael.grigorov@konsulko.com>
Signed-off-by: Georgi Vlaev <georgi.vlaev@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/11305
Reviewed-by: Leon Anavi <leon.anavi@konsulko.com>
Reviewed-by: Thomas Rini <trini@konsulko.com>
Reviewed-by: Matt Porter <mporter@konsulko.com>
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>