linux-gta04: bump SRCREV for more fixes and upgrade to 3.12.7

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
distro-feed-configs: Move SUPPORTED_EXTRA_ARCHS to defaulttunes.inc

* add spitz, so that I don't need to set it in local.conf

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>